Main  Lib. 
>igric.  Dept. 


WORKS    OF    H.    M.   WILSON 

PUBLISHED     BY 

JOHN  WILEY  &  SONS,  INC. 


Topographic,     Trigonometric    and     Geodetic     Sur= 
veyinjc. 

Including  Geographic,  Exploratory,  and  Military 
Mapping,  with  Hints  on  Camping,  Emergency  Sur- 
gery and  Photography.  Third  Edition,  Revised. 
Illustrated  by  18  engraved  colored  plates  and  205 
half-tone  plates  and  cuts,  including  two  double- 
page  plates.  8vo,  xxx  +  gi2  pages.  Cloth,  $3.50. 

Irrigation  Engineering-. 

Part  I.  HYDROGRAPHY.  Part  II.  CANALS  AND 
CANAL  WORKS.  Part  III.  STORAGE  RESERVOIRS. 
Sixth  Edition,  Revised  and  Enlarged.  8vo,  xxix  -\- 
625  pages;  38  full-page  plates  and  195  figures,  in- 
cluding many  half-tones.  $4.00. 


IRRIGATION  ENGINEERING 


BY 


ARTHUR  POWELL  DAVIS,  D.Sc 

Mem.  Ant.  Soc.  C.E.;    Director  and  Chief  Engineer  U.  S.  Reclamation 
A  utJior  of  "  Irrigation  IVorks  Constructed  by 
the  United  States,"  etc. 


AND 


HERBERT  M.  WILSON,  C.E. 

Mem.  Am.  Soc.  C.E.;    Former  Chief  Engineer  and  Irrigation 

Engineer,    U.    S.    Geological  Survey;    Author  of 

"  Topographic  Surveying,"  etc. 


SEVENTH  EDITION,  REVISED  AND  ENLARGED 
TOTAL   ISSUE   TWELVE   THOUSAND 


NEW  YORK 

JOHN  WILEY  &   SONS,   INC. 

LONDON:  CHAPMAN  &  HALL,  LIMITED 
1919 


COPYRIGHT,  1896,  1903,  1905,  1909 
By  HERBERT  M.  WILSON 


COPYRIGHT,  1919 
By  ARTHUR  P.  DAVIS  and  HERBERT  M.  WILSON 


PRESS  OF 

BRAUNWORTH    &   CO. 

BOOK    MANUFACTURERS 

BROOKLYN,   N.  Y. 


PREFACE  TO  SEVENTH  EDITION 


THE  first  edition  of  "  Irrigation  Engineering,"  was  a  pioneer 
in  its  field,  and  quickly  took  its  place  as  the  recognized  stand- 
ard therein,  as  indicated  by  its  passage  through  six  successive 
editions. 

At  the  date  of  the  first  edition  and  in  fact,  some  time  later, 
the  large  irrigation  works  of  engineering  interest  were  mostly 
in  India  and  Egypt.  Mr.  Wilson's  familiarity  with  those  works, 
based  largely  on  personal  contact  with  them  and  their  builders 
and  operators,  gave  the  early  editions  of  his  work  a  special 
value  as  contributions  to  western  knowledge  of  this  subject. 

The  subsequent  activity  in  irrigation  in  other  parts  of 
the  world,  especially  in  the  United  States,  together  with  similar 
developments  in  related  lines  of  municipal  water  supply  and 
hydro-electric  construction,  have  presented  new  problems  and 
evolved  new  solutions  of  old  ones  to  such  an  extent  that  what 
might  almost  be  called  a  new  science  has  been  developed,  requir- 
ing different  treatment.  Moreover,  social,  political  and  eco- 
nomic conditions  in  America  are  radically  different  from  those 
in  the  Orient,  and  this  imposes  very  different  conditions  and 
limitations  upon  the  practice  of  irrigation  engineering. 

Sir  William  Willcocks,  on  his  visit  to  America,  said  he  was 
accustomed  to  look  upon  the  irrigation  industry  as  one  abso- 
lutely dependent  upon  cheap  labor  like  that  of  Asia  and  Africa, 
and  that  his  chief  interest  in  examining  American  irrigation 
was  to  learn  how  it  was  that  irrigation  could  be  practiced  at 
all  in  America.  American  irrigation  practice  therefore  is 
very  different  from  that  of  India,  and  has  been  largely  developed 
quite  recently. 


394095 


VI  PREFACE   TO   THE  SEVENTH  EDITION 

When  .the  undersigned  was  requested  to  revise  this  work 
for  a  seventh  edition,  he  undertook  the  task  under  the  handi- 
cap of  having  his  time  very  fully  occupied  by  official  duties, 
without  fully  realizing  the  magnitude  of  the  task. 

The  material  of  the  sixth  edition  relating  to  sewage  disposal 
and  irrigation  and  to  subterranean  water  supply  has  been 
liberally  used.  A  few  other  portions  have  been  used  in  part, 
and  about  40  per  cent  of  the  illustrations  have  been  utilized. 
In  the  main  the  work  has  been  rewritten  and  rearranged,  and 
much  new  material  has  been  added. 

The  principal  difference  introduced  is  the  treatment  of 
soils,  plant  food,  operation  and  maintenance,  and  other  lines 
of  work  where  the  duties  of  the  irrigation  engineer  come  in 
contact  with  the  irrigator,  such  as  the  preparation  of  land, 
the  duty  of  water  and  its  application  to  the  land.  No  attempt 
has  been  made  to  treat  these  nor  indeed  any  other  branches 
of  the  subject  exhaustively,  which  cannot  be  done  within  the 
limits  of  such  a  work  as  this.  It  is  hoped  the  results  justify 
their  publication,  and  will  continue  the  usefulness  of  the  work 
so  well  pioneered  by  Mr.  Wilson. 

In  writing  and  compiling  this  work  much  assistance  has 
of  course  been  drawn  from  existing  literature,  and  references 
are  made  to  the  same  at  the  ends  of  chapters,  and  in  the  text. 

A.  P.  D. 


TABLE  OF  CONTENTS 


PAGE 

LIST  OF  ILLUSTRATIONS .  Xvii 


CHAPTER  I 

INTRODUCTION i 

1.  History 2 

2.  Extent  of  Irrigation 4 

3.  Malarial  Effects  of  Irrigation 5 


CHAPTER  II 

SOILS 7 

1 .  Residual 7 

2.  Alluvial 7 

3.  Eolian 7 

4.  Glacial 7 

5.  Injurious  Salts 8 

a.  Percentage  in  Soils 9 

b.  Resistance  of  Various  Crops 1 1 

6.  Remedies  for  Alkali 12 

a.  Leaching 12 

b.  Plowing 13 

c.  Growth  of  Suitable  Plants 13 

d.  Mulching 14 

e.  Gypsum. 14 


CHAPTER   III 

SOIL  MOISTURE - 16 

1.  Free  Water 16 

2.  Capillary  Water 16 

3.  Hygroscopic  Water 16 

4.  Capillary  Movement 17 

5.  Optimum  Water  Supply 18 

6.  Wilting  Coefficient 20 

7.  Water  Required  for  One  Irrigation 20 

vii 


Vlll  CONTENTS 

CHAPTER  IV 

PAGE 

PLANT  FOOD 22 

1.  Functions  of  Water  in  Plant  Growth 22 

2.  Mineral  Foods 23 

3.  Fertilizing  Effect  of  Sediments 25 

CHAPTER  V 

WATER  SUPPLY 27 

1.  Causes  of  Rainfall 27 

2.  Types  of  Rainfall 32 

a.  Pacific  Type 32 

.    b.  Rocky  Mountain  Type 35 

3.  Stream  Flow 37 

4.  Laws  of  Runoff 40 

a.  Drainage  Area 40 

b.  Rainfall 40 

c.  Character  of  Rainfall 41 

d.  Evaporation 41 

e.  Topography 41 

/.   Soil 41 

g.  Geologic  Structure 41 

h.  Vegetation 41 

5.  Discharge  of  Western  Streams 42 

6.  Subsurface  Water  Sources 45 

a.  Rate  of  Percolation 46 

b.  Permeability  of  Soils 47 

7.  Artesian  Wells 48 

a.  Examples 50 

b.  Capacity 51 

c.  Storage  of  Artesian  Water 51 

d.  Size  of  Well 52 

e.  Methods  of  Drilling 53 

/.   Varieties  of  Drilling  Machines 53 

g.  Process  of  Drilling 54 

h.  Capacity  of  Common  Wells 57 

8.  Tunneling  for  Water 59 

9.  Other  Subsurface  Water  Sources 61 

10.  Character  of  Water 61 


CHAPTER   VI 

EVAPORATION .' 65 

1.  Measurement  of  Evaporation 66 

2.  Amount  of  Evaporation 68 

3.  Evaporation  from  Snow  and  Ice 68 


CONTENTS  ix 

PAGE 

4.  Evaporation  from  Earth 69 

5.  Effect  on  Water  Storage 70 

CHAPTER  VII 

PUMPING  FOR  IRRIGATION 73 

1.  Ground- water  Supply 74 

2 .  Windmills 75 

3.  Water-wheels 78 

a.  Undershot 79 

b.  Overshot 81 

c.  Turbines 82 

d .  Pelton  Water-wheels 84 

4.  Internal  Combustion  Engines 84 

5.  Hot  Air,  Gasoline  and  Alcohol  Pumping  Engines 85 

6.  Steam  Power 86 

7.  Pumps 86 

8.  Direct  Pumping 90 

9.  Hydraulic  Ram 91 

10.  Air-lift  Pumping 92 

11.  Hydro-electric  Pumping 92 

12.  Humphrey  Direct-explosion  Pump 95 

13.  Rice  Irrigation 97 


CHAPTER   VIII 

IRRIGABLE  LANDS 99 

1 .  Topography 99 

2.  Soil  Survey 101 

3.  Preparation  of  Land 104 

a.  Clearing 104 

b.  Leveling 107 

c.  Ditching no 


CHAPTER  IX 

APPLICATION  OF  WATER  TO  THE  LAND in 

1.  Methods  of  Irrigation in 

a.  Free  Flooding in 

b.  Border  Method 112 

c.  Furrow  Irrigation 117 

d.  Corrugation  System 119 

e.  Leveling 1 20 

2.  Sewage  Disposal 123 

3.  Sewage  Irrigation 127 

4.  Fertilizing  Effects  of  Sewage 128 


CONTENTS 


5.  Effects  of  Sewage  Irrigation  on  Health 129 

6.  Duty  of  Sewage 130 

7.  Methods  of  Applying  Sewage 130 

8.  Sub-irrigation 133 

CHAPTER  X 

DUTY  OF  WATER 137 

1.  Length  of  Season 138 

2.  Natural  Rainfall 138 

3.  Soil  Conditions 139 

4.  Crops  Raised 139 

5.  Preparation  of  Ground  and  Ditches 140 

6.  Skill  of  the  Irrigator • 140 

7.  Care  with  which  Water  is  Used 140 

8.  Cultivation 140 

9.  Utah  Experiments 141 

10.  Agricultural  Department  Experiments 143 

11.  U.  S.  Reclamation  Service 144 

12.  Inquiry  of  American  Society  of  Agricultural  Engineers 148 


CHAPTER  XI 

MEASUREMENT  OF  IRRIGATION  WATER 153 

1 .  Gaging  Streams 153 

2.  Use  of  Current  Meter 157 

3.  Hydraulic  Formulae 163 

4.  Measurement  of  Water  to  the  User 164 

5.  Measuring  Devices 165 

a.  Weirs 166 

b.  Orifices .  .  .  168 

c.  Hanna  Meter 1 73 

d.  Azusa  Hydrant 1 73 

e.  Foote  Measuring  Box 1 73 

f.  Dethridge  Meter 1 75 

"g.  Hill  Meter .176 

h.  Grant-Mitchell  Meter 177 

i.   Venturi  Meter 177 

j.  Venturi  Flume 1 78 


CHAPTER  XII 

DRAINAGE 184 

1.  Signs  of  Seepage 185 

2.  Classification  of  Drains 191 

3.  Design  of  a  Drainage  System 193 


CONTENTS  xi 


4.  Location  of  Drains 193 

5.  Depth .195 

6.  Capacity 195 

7.  Form  of  Tile 196 

8.  Manholes 197 

9.  Wooden  Drains 198 

10.  Cement  Pipe  Drains 198 

11.  Drainage  Works  of  U.  S.  Reclamation  Service 200 


CHAPTER  XIII 

CANALS  AND  LATERALS 202 

1 .  Capacity  of  Canals 202 

2.  Design 205 

3.  Alinement 212 

4.  Velocity 215 

5.  Lateral  Systems 217 

6.  Design  of  Laterals 220 

7.  Capacity  of  Laterals 221 

8.  Location  of  Laterals 222 

9.  Abnormal  Leakage  from  Canals 224 

10.  Construction  of  Canals 227 

11.  Canal  Losses  and  their  Prevention 233 

12.  Seepage  Losses _ 234 

13.  Seepage  Formula 235 

14.  Canal  Lining 236 

15.  Amount  of  Return  Seepage 245 


CHAPTER  XIV 

CANAL  STRUCTURES 247 

1 .  Classification 247 

2.  Location  of  Headworks 247 

3.  Canal  Headgates 248 

4.  Turnouts 263 

5.  Canal  Spillways 271 

6.  Checks,  Drops  and  Chutes 284 

7.  Protection  against  Erosion 290 

Drainage  Crossings 293 

Flumes 299 

10.  Behavior  of  Various  Metals  in  Presence  of  Alkali 308 

11.  Culverts 314 

12.  Pipes .  323 

13.  Tunnels 330 

14.  Highway  Crossings .335 

15.  Sand  Traps 337 


xii  CONTENTS 


CHAPTER  XV 

PAGE 

STORAGE  RESERVOIRS 342 

1.  Classes  of  Storage  Works 342 

2.  Selection  of  a  Reservoir  Site 343 

3.  Geology  of  Reservoir  Sites 344 

4.  Leakage  from  Reservoirs 346 

5.  Survey  of  Reservoir  Sites 353 

6.  Spillway  Provisions 354 

7.  Outlet  Works 358 


CHAPTER   XVI 

SEDIMENTATION  OF  RESERVOIRS 370 

1.  Measurement  of  Sediment 371 

2.  Sediment  Rolled  on  Bottom  of  Stream 373 

3.  Removal  of  Silt  from  Reservoirs 376 


CHAPTER  XVII 

DAMS 381 

1.  Conditions  of  Safety 381 

2.  Diversion  Dams  or  Weirs 382 

a.  Timber  Dams 382 

b.  Rectangular  Pile  Weirs 384 

c.  Open  and  Closed  Weirs 386 

d.  Flashboard  Weirs 388 

e.  Indian  Type  Weirs 390 

/.   Automatic  Gates 392 

g.  Automatic  Drop  Shutters 392 

h.  French  Type  of  Weir 394 

/.    Roller  Dams 394 

i.   Crib  Dams 401 

k.  Submerged  Dams 402 

3.  Storage  Dams 404 

a.  Earthen  Embankments ' 405 

b.  Foundations .   405 

c.  Springs  in  Foundations 408 

d.  Safe  Slopes 409 

e.  Slope  Protection 413 

/.    Percolation 417 

g.  Methods  of  Construction 424 

h.  Hydraulic  Fill 426 

4.  Rockfill  Dams 436 


CONTENTS  xiii 


CHAPTER  XVIII 

PAGE 

MASONRY  DAMS 442 

1.  Classification 443 

2.  Methods  of  Failure 44 

3.  Pressures  in  Masonry 444 

4.  Failure  by  Sliding 447 

5.  Failure  by  Overturning 449 

6.  Miscellaneous  Forces 450 

7.  Design  of  Gravity  Dams 453 

8.  Design  of  Arch  Dams 469 

9.  Masonry  Overfall  Dams 475 

10.  Hollow  Concrete  Dams 478 

1 1 .  Steel  Dams 487 

a.  Steel  Dam,  Ash  Fork,  Arizona 487 

12.  Foundations  for  Masonry  Dams 490 

13.  Exploring  Foundation 493 


CHAPTER  XIX 

WATER  RIGHTS 496 

1.  Nature  of  Property  in  Water 496 

2.  Riparian  Doctrine 496 

3.  Doctrine  of  Appropriation 496 

4.  Appurtenance  to  Land 500 


CHAPTER  XX 

OPERATION  AND  MAINTENANCE 502 

1.  Personnel 502 

a.  Manager 502 

b.  Canal  Superintendent 502 

c.  Canal  Riders 503 

d.  Hydrographers 503 

e.  Cooperation  with  Water  Users 504 

2.  Economy  of  Water 504 

3.  Wanton  Waste 511 

4.  Rotation  Delivery 512 

5.  Basis  of  Charges 514 

6.  Cultivation 515 

7.  Winter  Operation 516 

8.  Maintenance 518 

9.  Erosion  of  Canal  Banks 519 

10.  Silt  Deposits 520 

11.  Alkali 521 


XIV  CONTEXTS 

PAGE 

12.  Aquatic  Plants 521 

13.  Wind  Erosion 524 

14.  Noxious  Plants 525 

15.  Burrowing  Animals 525 

16.  Land  Slides 526 


CHAPTER  XXI 

INVESTIGATION  OF  A  PROJECT 528 

1.  Reconnaissance 528 

2.  Surveys 528 

3.  Estimates  of  Cost 531 

a.  Bias 531 

b.  Influence 532 

c.  Inaccurate  Data 532 

d.  Omissions 532 


CHAPTER  XXII 

SPECIFICATIONS  FOR  CONSTRUCTION 534 

1.  Specifications  for  Arrowrock  Dam 535 

2.  Contract  Specifications  of  the  Reclamation  Sendee 547 

a.  General  Requirements 547 

b.  Special  Requirements 554 

3.  Standard  Paragraphs  for  Purchase  of  Material 555 

4.  Earthwork  on  Canals 556 

5.  Concrete 559 

6.  Structural  Steel 561 

7.  Steel  Reinforcement  Bars 562 

8.  Gray  Iron  Castings 563 

9.  Malleable  Castings 564 

10.  Steel  Castings 564 

1 1 .  Cement 565 

12.  Continuous  Wood  Stave  Pipe .  566 

13.  Machine  Banded  Wood  Stave  Pipe 569 

14.  Laying  Machine  Banded  Wood  Stave  Pipe 571 

15.  Steel  Pipe -572 

16.  Jointed  Reinforced  Concrete  Pipe 574 

1 7.  Metal  Flumes 576 

18.  Steel  Highway  Bridges 579 

19.  Tunnels '. 584 

20.  Telephone  System 586 

21.  Vitrified  Pipe,  for  Culverts 590 


CONTENTS  xv 


CHAPTER  XXIII 

PAGE 

TABLES 592 

1.  Extreme  Flood  Discharges , . . .  593 

2.  Table  of  Reservoirs 598 

3.  List  of  Earth  and  Rockfill  Dams .' 599 

4.  List  of  High  Masonry  Dams 600 

5.  Velocity  Tables 602 

6.  Tables  of  Area  and  Hydraulic  Radius 611 

7.  Velocity  Heads 614 

8.  Weights  of  Various  Substances 615 

9.  Convenient  Equivalents 616 


LIST  OF    ILLUSTRATIONS 


FIG.  PAGE 

1.  Mean  Annual  Precipitation  in  the  United  States 29 

2.  Percentage  of  Annual  Precipitation  Occurring  between   April   ist  and 

September  3oth 30 

3.  Mean  Precipitation  Occurring  between  April  ist  and  September  3oth.  .  .  31 

4.  Diagram  Showing  Effect  of  Topography  on  Rainfall  in  California 33 

5.  Discharge  of  San  Joaquin  River  at  Herndon,  California,  1900 33 

6.  Discharge  of  Neosho  River  near  lola,  Kansas,  1900 34 

7.  Discharge  of  Boise  River  at  Boise,  Idaho,  1899 34 

8.  Discharge  of  Salt  River  at  McDowell,  Arizona,  1899 35 

9.  Discharge  of  Green  River  at  Green  River,  Wyoming,  1899 35 

10.  Types  of  Monthly   Distribution   of  Precipitation  in  the  United  States. 

(After  A.  J.  Henry.) 36 

11.  Ideal  Section  Illustrating  Condition  of  Artesian  Wells 49 

12.  Ideal  Section  Illustrating  Thinning  out  of  Water-bearing  Stratum 50 

13.  Portable  Artesian  Well  Drilling  Rig 55 

14.  Subterranean  Water  Tunnel  and  Feed  Wells,  California 60 

15.  Gathering  Cribs,  Citizen's  Water  Company,  Denver,  Colorado 61 

16.  Evaporating  Pan 67 

17.  Windmill  and  Reservoir  near  Garden  City.  Kansas 88 

18.  Battery  of  Hydraulic  Rams,  Yakima  Valley,  Washington 88 

19.  Undershot  Waterwheel 89 

20.  Current  Wheel  or  Noria,  Lifting  Water  from  Salmon  River  for  Irrigation .  89 

21.  Diagram  Illustrating  Principle  of  Hydraulic  Ram 91 

22.  Scoop  Wheel  Lifting  Water  3^  Feet  60  per  Cent  Efficient 94 

23.  Direct-explosion  Pumping  Plant  to  Raise  Irrigating  Water  37  Feet 95 

24.  Shoshone  Desert  before  Irrigation 100 

25.  Shoshone  Desert  after  Irrigation 101 

26.  Slip  Scraper 106 

27.  Adjustable  V  for  Making  Head  Ditches 107 

28.  Leveling  New  Lands,  Idaho .- 108 

29.  Fresno  Scraper 109 

30.  Float  for  Leveling  Irrigable  Lands no 

31.  Using  Canvas  Dam 113 

32.  Steel  Dams "3 

33.  Diverting  Water  from  Head  Ditch,  Canvas  Dam,  Shoshone  Valley,  Wyo- 

ming   i  M 

xvii 


XVlll  LIST  OF  ILLUSTRATIONS 


34.  Drawing  Water  from  Head  Ditch  through  Small  Pipes,  Riverside,  Cali- 

fornia   j  i  5 

35.  Field  Prepared  for  Irrigation  by  Checks 1 16 

36.  Border  Irrigation  in  Nevada 116 

37.  Diagram  Illustrating  Flooding  in  Rectangular  Blocks  or  Checks.     Cowgill.  1 1 7 

38.  Orchard   Irrigation  by  Furrow  Method,   Yakima  Valley,   Washington.  118 

39.  Furrow  Irrigation  of  Cabbages,  Yuma,  Arizona 119 

40.  Furrow  Irrigation  on  Terraced  Hillside,  California 1 20 

41.  Irrigating  Orchard  by  Terraced  Basins  on  Hillside 121 

42.  Orange  Trees  Irrigated  by  Check  System,  Salt  River,  Arizona 122 

43.  Furrow  Irrigation  of  Orange  Grove,  Riverside,  California 122 

44.  Extent  of  Percolation  from  Small  Furrows:    A,  in  Loose  Loam;    B,   in 

Hardpan;  C,  in  Impervious  Grit 1 23 

45.  Irrigating  with  Large  Head  by  Border  Method  from  Cement  Head  Ditch, 

Salt  River  Valley,  Arizona 1 24 

46.  Irrigating  Corn  with  Sewage,  Plainfield,  N.  J 125 

47.  Furrow  Irrigation  of  Apple  Orchard,  Idaho 125 

48.  Haskell  Current  Meter 155 

49.  Price  Electric  and  Acoustic  Meters 156 

50.  Water  Stage  Recorders 160 

51.  Cable  Gaging  Station  with  Automatic  Continuous  Recording  Gage 161 

52.  Cable  and  Car  Gaging  Station 161 

53.  Wire  and  Boat  Gaging  Station 162 

54.  Rectangular  Measuring  Weir 173 

55.  Foote's  Measuring  Weir,  A ;  Water  Devisor.  B 174 

56.  Australian  Water  Meter 177 

57.  Venturi  Meter  and  Recording  Device  on  Lateral  Head 177 

58.  Curve  Showing  Fluctuation  of  Ground  Water  and  Application  of  Irriga- 

tion  Water   in    the    Rio    Grande   Valley.     After   Burkholder 187 

59.  Curve  Showing  the  Seasonal  fluctuation  and  Yearly  Rise  of  Ground  Water 

in  Boise  Valley,  Idaho.     After  Burkholder 188 

60.  Curve  showing  Rise  of  Ground  Water  before  Construction  of  Drains  and 

Effect  of  Drains.  Boise  Valley,  Idaho.     After  Burkholder 189 

61.  Excavating  Trench  for  Tile  Drain,  Montana 192 

62.  Dragline  Excavator  on  Drainage  Work,  Idaho 192 

63.  Cross-sections  of  Interstate  Canal,  North  Platte  Valley,  Nebraska 204 

64.  Canal  Cross-sections  for  Varying  Bed  Widths 206 

65.  Various  Canal  Cross-sections 206 

66.  Rock  Cross  Section,  Turlock  Canal 207 

67.  Rock  Cross-section,  Umatilla  Canal 208 

68.  Cross-section  of  Galloway  Canal  in  Sand,  Showing  Sub-grade 211 

69.  Typical  Section  of  Lined  Canal 211 

70.  Tunnel  and  Canal  Sections,  Tieton  Main  Canal 213 

71.  Diagram  Illustrating  Distributary  System 218 

72.  Cavity  Developed  in  Canal  Bed,  Flathead  Reservation,  Montana 225 

73.  Cave  Developed  in  Bottom  of  Canal,  Flathead  Indian  Reservation 226 

74.  Building  Lateral  in  Montana  with  Ditching  Machine 228 


LIST  OF  ILLUSTRATIONS  xix 

FIG.  PAGE 

75.  Building  Irrigation  Lateral  in  Montana  with  Elevating  Grader 228 

76.  Building  Canal  with  Elevating  Grader 229 

77.  Building  Canal  with  Fresno  Scrapers 233 

78.  Cross-section  of  Santa  Ana  Canal,  Lined  with  Boulders  Set  in  Cement.  .  .  237 

79.  Check  Gates  and  Canal  Lined  on  One  Side.     Interstate  Canal 239 

80.  Semicircular  Concrete  Lined  Section  of  Main  Canal,  Umatilla  Valley, 

Oregon 239 

ST.  Concrete  Lining  Truckee-Carson  Canal,  Nevada 240 

82.  Reinforced  Concrete  Lining,  Tieton  Canal,  Washington 241 

83.  Transition  from  Rock  to  Earth  Cross-section  Lined  Canal 242 

84.  Lining  Canal  with  Concrete,  Idaho 244 

85.  Cross-section  of  Corbett  Weir,  Shoshone  Project,  Wyoming 248 

86.  Plan   of   Corbett   Dam   and   Headworks,    Shoshone   Project,   Wyoming.  249 

87.  Wooden  Gate,  Leasburg  Canal  Regulator,   Rio   Grande,   New  Mexico.  250 

88.  Iron  Regulator  Gate,  Minidoka  Canal,  Idaho 250 

89.  Cast-iron  Sluice-gate,  Interstate  Canal,  Nebraska- Wyoming 251 

90.  Diversion  Works,  Lost  River,  Oregon 252 

Regulator  Gates,  Laguna  Weir,  Colorado  River 253 

Inclined,  Falling  Regulator  Gates,  Goulburn  Canal,  Australia 254 

Sunnyside  Dam,  Canal  and  Headworks,  Yakima  Valley.     Headgates  in 

Line  with  Dam 255 

94.  Regulating  Gates  and  Sluice  Gates  at  Right  Angles  to  Each  Other,  Yuma 

Main  Canal,  California 256 

95.  Whalen  Diversion  Dam  and  Headgates,  Normal  to  Dam,  North  Platte 

River,  Wyoming 257 

96.  Sprague  River  Dam,  Klamath  Indian  Reservation,  Oregon 258 

97.  Plan  and  Elevation  of  Headworks,  Interstate  Canal,  North  Platte  River, 

Wyoming 259 

98.  Jackson  Lake  Dam,  Downstream  Face,  Wyoming 260 

99.  Headgates  and  Sluice  Gates,  Montrose  and  Delta  Canal,  Umcompahgre 

Valley,  Colorado.     Obtuse  angle 260 

100.  Division  Gates  and  Drops  on  Tsar  Canal  near  Byram  Ali,  Murgab  Valley, 

Turkestan 261 

101.  Headworks  of  Sultan  Yab  Canal  at  Sultan  Bend  Reservoir  on  Murgab 

River,  Turkestan 261 

102.  Cross-section  and  Elevation  of  Regulator  Gates,  Folsom  Canal 262 

103.  Wooden  Head  to  Lateral,  Sun  River  Canal,  Montana 263 

104.  Concrete    Check    and    Farm    Turnout    with    Inclined    Valve 264 

105.  Cast-iron  Valve  on  Small  Lateral  Turnout 265 

106.  Standard  Turnout,  Vitrified  or  Concrete  Pipe,  U.  S.  R.  S\ 266 

107.  Standard  Turnout  Box  Concrete,  U.  S.  R.  S 267 

108.  Reinforced  Concrete  Turnout  with  10  Foot  Drop,  Garland  Canal,  Wyo- 

ming   268 

109.  Cast-iron    Gates  for   Laterals,    Interstate   Canal,   Wyoming-Nebraska.  269 

no.  Reinforced  Concrete  Turnout  for  Lateral 270 

in.  Lateral  Headgates,  North  Platte  Valley,  Nebraska 271 

112.  Standard  Spillway,  Length  of  Weir  less  than  100  Feet.  U.  S.  R.  S 272 


XX  LIST  OF  ILLUSTRATIONS 

FIG.  PAGE 

113.  Standard  Spillway,  Length  of  Weir  over  TOO  Feet.     U.  S.  R.  S 273 

114.  Keno  Canal  Spillway,  Klamath  Falls,  Oregon 274 

115.  Plan  and  Section  of  Siphon  Spillway,  on  Canal  in  Colorado  Valley,  Cal.  276 

116.  Spillway,  Fort  Shaw  Canal,  Montana 277 

117.  Standard  Sluiceway,  Lower  Yellowstone  Canal,  Montana 278 

1 1 8.  Waste  way,  Lower  Truckee  Canal,  Nevada 279 

119.  Tieton  Main  Canal,  Lined  Section 281 

120.  Concrete  Drop  with  Water  Cushion,  Truckee-Carson  Canal,  Nevada  283 

121.  Notch  Drop,  Chenab  Canal,  India 284 

122.  Cross-section  of  Fall.     Bear  River  Canal 285 

123.  Notch  Drop,  Interstate  Canal,  Wyoming-Nebraska 286 

124.  Timber  Drop,  Lower  Yellowstone  Laterals,  Montana 287 

125.  By-pass  Feeder  from  Upper  to  Lower  Canal,  Umatilla  Project,  Oregon  288 

126.  Cylinder  Drop  on  Franklin  Canal,  Rio  Grande  Valley,  Texas 289 

127.  Series  of  Concrete  Drops  on  South  Canal,  Uncompahgre  Valley,  Colorado.  290 

128.  Concrete  Chute  and  Stilling  Basin,  Boise  Valley,  Idaho 291 

129.  Reinforced  Concrete  Chute,  Okanogan  Project,  Washington 294 

130.  Pipe  Inlet,  Reno  Coulee,  Lower  Yellowstone  Canal,  Montana 294 

131.  Elevation  and  Cross-section  of  Iron  Flume  on  Corinne  Branch,  Bear 

River  Canal,  Utah 295 

132.  Standard,  Reinforced,  Concrete  Flume,  Reclamation  Service 296 

133.  Circular  Reinforced  Concrete  Flume  and  Trestle,  Tieton  Canal,  Wash- 

ington   297 

134.  Head  works  of  Cavour  Canal,  Po  River,  Italy 298 

135.  Brick  Aqueduct  Carrying  Cavour  Canal,  Po  Valley,  Italy 298 

136.  Bench  Flume,   High  Line   Canal,   Colorado,   Spillway  in   Foreground.  300 

137.  View  of  Solani  Aqueduct,  Ganges  Canal,  India 301 

138.  Cross-section  of  San  Diego  Flume,  California 302 

139.  Cross-section  of  Stave  and  Binder  Flume,  Santa  Ana  Canal,   California.  302 

140.  Section  through  Reinforced  Concrete  Aqueduct,  Interstate  Canal,  Wyo- 

ming-Nebraska    303 

141.  Mill  Creek   Flume,   Steel  Frame  and  Bridge,   Santa  Ana  Canal,  Cal.  304 

142.  Steel  Flume,  Tieton  Distribution  System,  Yakima  Valley,  Washington.  306 

143.  Steel  Flume  Crossing  Eight-mile  Creek,  Boise  Valley,  Idaho 307 

144.  Half  Longitudinal  Section,  Reinforced   Concrete  Aqueduct,  Interstate 

Canal,  Wyoming-Nebraska 308 

145.  Reinforced  Concrete  Aqueduct,  Spring  Canyon,  Interstate  Canal,  Wyom- 

ming-Nebraska .-  •  •  •   310 

146.  Concrete  Flume,  Spanish  Fork  Valley,  Utah,  Showing  Warped  Transition 

from  Canal  to  Flume 310 

147.  View  of  Ranipur  Superpassage,  Ganges  Canal,  India 311 

148.  Continuous  Wood   Stave  Pressure  Pipe,   Idaho  Irrigation  Company's 

Canal 312 

149.  Elevation  and  Cross-section  of  Nadrai  Aqueduct,  Lower  Ganges  Canal.  313 

150.  Reinforced    Concrete    Culvert,    Lower    Yellowstone    Canal,    Montana.  315 

151.  Burn's    Creek    Superpassage,    Lower    Yellowstone    Canal,    Montana.  316 

152.  Inlet  to  Rawhide  Siphon,  Interstate  Canal,  Wyoming-Nebraska 317 


LIST  OF  ILLUSTRATIONS  XXI 

FIG.  PAGE 

153.  Siphon  Crossing  under  Rawhide  Creek,  Interstate  Canal,  Wyoming- 

Nebraska 317 

154.  Reinforced  Concrete  Twin  Siphon,  Interstate  Canal,  Wyoming-Nebraska.  319 

155.  Reinforced  Concrete  Twin  Siphon >  Fox  Creek  Crossing,  Lower  Yellow- 

stone Canal,  Montana 320 

156.  Main  Canal,  Concrete  Lined,  Okanogan  Project,  Washington 321 

157.  Happy  Canyon  Steel  Flume,  Uncompahgre  Valley,  Colorado 322 

158.  Steel  Bridge  and  Wood  Stave  Pressure  Pipe,  Yakima  Valley  near  Prosser, 

Washington 327 

159.  Steel  Forms  and  Reinforcement  for  Concrete  Pressure  Pipe,  Boise  Valley, 

Idaho 328 

1 60.  Removing  Inside  Steel  Forms  from  Concrete  Pressure  Pipe 329 

161.  Manhole  and  Concrete  Collars  on  Concrete  Pressure  Pipe,  Boise  Valley, 

Idaho 329 

162.  High  Line  Canal,  Spanish  Fork  Valley,  Utah,  Covered  to  Protect  Against 

Land  and  Snow  Slides 336 

163.  Headgates,  Sluicegates  and  Sand  Basins,  High  Line  Canal,  Spanish  Fork, 

Utah 336 

164.  Cross-section  of  Sandbox,  Santa  Ana  Canal 338 

165.  Sandbox,  Leasburg  Canal,  Rio  Grande  Valley,  New  Mexico 339 

1 66.  Standard  Sluiceway  and  Sandgate,  Lower  Yellowstone  Canal,  Montana- 

North  Dakota - 340 

167.  Curves  of  Seepage  from  Deerflat  Reservoir  Showing  Improvement  with 

Use 348 

168.  Gatehouse  Conconully  Dam,  Washington 360 

169.  Vertical  Lift  Outlet  Gate,  Fay  Lake  Reservoir,  Arizona 361 

170.  Valve  Plugs:     A,  Sweetwater,  and  B,  Hemet  Dams 362 

171.  Outlet  WTorks  Lahontan  Dam,  Carson  River,  Nevada 363 

172.  Section  of  Balanced  Valve,  Arrowrock  Dam,  Boise  River,  Idaho 365 

173.  Outlet  Conduit  Keechelus  Dam,  Washington,  Showing  Concrete  Cut-off 

Collars,  Core  Wall  and  Track  for  Backfilling  on  Left 366 

174.  Butterfly  Valve,  Minatare  Dam.  Nebraska 366 

175.  Elevation  and  Section  of  Butterfly  Valve 367 

176.  Needle  Valve  in  Outlet  Conduit,  Needle  Dam,  North  Platte  Valley, 

Nebraska 368 

177.  Trap  for  Measuring  Sand  Rolling  on  Bottom  of  Stream 375 

178.  Folsom  Canal,  View  of  Weir  and  Regulator 383 

179.  Folsom  Canal,  Plan  and  Cross-section  of  Weir 385 

180.  Plan  and  Section  of  Laguna  Dam,  Colorado  River 385 

181.  Cross-section  of  Lower  Yellowstone  Weir,  Montana : 387 

182.  Kern  River  Diversion  Weir,  Head  of  Galloway  Canal 389 

183.  Cross-section  of  Open  Weir,  Galloway  Canal 390 

184.  Cross-section  of  Indian  Weirs 391 

185.  Cross-section  of  Shutter  on  Soane  Weir,  India 392 

1 86.  Automatic  Drop  Shutter,  Betwa  Weir,  India 393 

187.  Falling  Sluice  Gate,  Soane  Canal,  India 395 

188.  View  of  Open  Weir  on  River  Seine,  France 396 


xxii  LIST  OF  ILLUSTRATIONS 

FIG.  PAGE 

189.  View  of  Goulburn  Weir,  Australia 397 

190.  View  of  Rolling  Dam.  Grand  River,  Colorado 398 

191.  Section  through  Body  of  7o-foot  Roller  Dam,  Grand  River,  Colorado.  399 

192.  Section  through  Driven  Hand  7o-foot  Roller 400 

193.  Cross-section  of  Bear  River  Crib  Weir 401 

194.  Cross-section  of  Upper  Coffer  Dam.  Arrowrock  Dam,  Boise  River,  Idaho .  402 

195.  View  of  San  Fernando  Submerged  Dam 403 

196.  Sections  of  Owl  Creek  Storage  Dam,  Belle  Fourche  Valley,  South  Dakota.  406 

197.  Plan  of  Lahontan  Dam,  Carson  River,  Nevada 408 

198.  Elevation  and  Cross-section  of  Strawberry  Dam,  Utah 410 

199.  Section  of  Kachess  Dam,  Yakima  Valley,  Washington 414 

200.  Profile,  Plan  and  Section  of  Upper  Deerflat  Embankment.  Boise  Valley, 

Idaho : 416 

201.  Owl  Creek  Dam  near  Belle  Fourche,  South  Dakota,  showing  Concrete 

Paving 418 

202.  Upper  Deerflat  Embankment  Showing  Beaching  of  Gravel  Slope 418 

203.  Wheeled  Scraper 425 

204.  Cold  Springs  Dam  under  Construction,  Umatilla  Valley,  Oregon 427 

205.  Grooved  Concrete  Roller 427 

206.  Dam  at  Necaxa,  Mexico 428 

207.  Trestles  on  Conconully  Dam,  Washington,  Showing  Method  of  Hydraulic 

Construction 431 

208.  Cross-section  of  Bumping  Lake  Dam,  Naches  River.  Washington 433 

209.  Section  of  Sherburne  Lakes  Dam  showing  Gravel  Core  and  Drains  to 

Provide  for  Seepage  Water 434 

210.  Sections  of  Conconully  Dam,  Salmon  Creek,  Washington 435 

211.  Rockfilled  Dam,  Snake  River,  Minidoka  Project,  Idaho 436 

212.  Plan  and  Cross-section  of  Bowman  Dam 437 

213.  Elevation,  Plan  and  Cross-section  of  Castlewood  Dam,  Colorado 438 

214.  Lower  Otay  Rockfilled  Dam,  California 439 

215.  Elevation  and  Cross-section  of  Walnut  Grove  Dam 440 

216.  Rockfilled  Steel  Core  Dam,  Lower  Otay,  California 440 

217.  Section  of  Elephant  Butte  Dam,  Rio  Grande,  New  Mexico 454 

218.  Elephant  Butte  Dam,  Cableways  and  Mixing  Plant,  Rio  Grande,  New 

Mexico 455 

219.  Elevation  of  Arrowrock  Dam,  Boise  River,  Idaho 458 

220.  Maximum  Section  of  Arrowrock  Dam , 459 

221.  Plan  of  Arrowrock  Dam,  Boise  River,  Idaho 460 

222.  Elephant  Butte  Dam  showing  Construction  in  Alternate  Columns 462 

223.  Cross-section  of  Periar  Dam,  India 463 

224.  Cross-section  of  New  Croton  Masonry  Dam,  New  York 464 

225.  Plan,   Cross-section   and  Outlet  Sluices,   San  Mateo  Dam,   California.  466 

226.  Plan  of  Roosevelt  Dam,  Arizona 467 

227.  Maximum  Cross-section  of  Roosevelt  Dam,  Arizona 468 

228.  Pathfinder  Dam,  North  Platte  River,  Wyoming,  Lower  Face  Showing 

Concrete  Ladder  and  6500  Second-feet  of  Water  Discharging  from 
Tunnel 470 


LIST  OF  ILLUSTRATIONS  xxiii 

FIG.  PAGE 

229.  Upper  Otay  Masonry  Dam,  California 471 

230.  Meerallum  Dam,  India.     Plan  and  Sections  of  One  Arch 472 

231.  Cross-section  of  Bear  Valley  Dam,  California 473 

232.  Plan  and  Elevation  of  Bear  Valley  Dam,  California 473 

233.  Shoshone  Dam,  Wyoming.     Analysis  of  Pressures 474 

234.  Cross-section  of  New  Holyoke  Weir,  Mass • 475 

235.  Cross-section  of  Granite  Reef  Weir,  Salt  River,  Arizona 476 

236.  Cross-section  of  Norwich  Water  Company's  Weir 477 

237.  Leasburg  Diversion  Weir,  Rio  Grande  Valley,  New  Mexico 478 

238.  Cross-section  of  Old  Croton  Dam,  New  York 479 

239.  McCall's  Ferry  Dam,  Susquehanna  River,  Pa.,  Showing  Steel  Forms 

Used  in  Construction 480 

240.  Cross-section  of  La  Grange  Overflow  Masonry  Dam,  California 480 

241.  Granite  Reef  Dam,  Salt  River,  in  Flood,  Showing  Hydraulic  Jump..  .  481 

242.  East  Park  Reservoir  Spillway,  Orland  Project,  California 482 

243.  Diversion   Dam,   East   Park   Feed    Canal,   Orland   Project,   California.  482 

244.  Elevation,  Plan  and  Section  of  Three  Miles  Falls  Dam,  Umatilla  River, 

Oregon. . 483 

245.  East  Park  Multiple  Arch  Spillway,  Orland  Project,  California 485 

246.  Cross-section  of  Iron  Weir,  Cohoes,  New  York 486 

247.  Cross-section  of  Reinforced  Concrete  Weir,  Theresa.  New  York 486 

248.  Steel  Dam,  Ash  Fork,  Arizona 488 

249.  Iron  Face  Rollerway  Weir,  Cohoes,  New  York 489 

250.  Standard  Horseshoe  and  Circular  Sections  of  Conduits 612 


IRRIGATION  ENGINEERING 


CHAPTER  I 
INTRODUCTION 

IRRIGATION  is  the  artificial  application  of  water  to  soil  to 
assist  in  the  production  of  crops.  Its  most  familiar  form  is 
the  sprinkling  of  lawns  in  both  arid  and  humid  regions,  and  the 
contrast  between  the  watered  and  unwatered  lawns,  even  in  a 
humid  climate,  illustrates  its  benefits.  Wherever  practiced, 
it  is  supplementary  to  the  natural  rainfall. 

Scientific  irrigation  involves  a  knowledge  of  the  available 
water  supply,  its  conservation  and  application  to  the  land,  the 
characteristics  and  needs  of  the  different  types  of  soil,  and  the 
requirements  of  the  various  crops  to  be  produced. 

In  general,  irrigation  is  most  extensively  practiced  in  arid 
regions  where  agriculture  without  it  is  precarious  or  impracti- 
cable, but  it  is  also  applied  to  lands  of  the  semi-arid  regions 
to  increase  the  yield,  and  to  special  crops  in  humid  regions, 
such  as  rice,  sugar  cane,  lawns,  garden  flowers  and  vegetables. 
In  fact  there  are  comparatively  few  regions  so  free  from  occa- 
sional drouth  that  irrigation  would  not  be  profitable  if  it  could 
be  cheaply  provided. 

The  surface  of  the  earth  is  composed  of  land  and  water, 
the  latter  being  roughly  three-fourths  of  the  area  and  not 
habitable  by  man.  Of  the  remaining  one-fourth  or  land  area, 
more  than  half  is  either  too  cold  or  too  rocky  for  cultivation, 
and  of  the  remainder  the  major  portion  is  too  arid  for  the  pro- 
duction of  crops,  and  only  in  part  useful  for  grazing  or  other 
purposes.  Even  of  the  humid  area,  a  very  large  part  is  in  tropi- 


2  INTRODUCTION 

cal  Africa  and  South  America,  ill-adapted  to  civilization  and 
development  by  means  known  at  present. 

Thus  the  area  naturally  available  for  cultivation  is  a  very 
small  proportion  of  the  whole,  but  can  in  places  be  increased 
by  artificially  applying  water  to  the  soil  where  nature  fails  to 
do  this. 

An  irrigated  region  has  certain  advantages  over  a  humid 
region  in  the  production  of  crops.  There  is  much  advantage 
in  being  able  to  apply  the  wrater  at  just  the  time  and  in  just 
the  quantity  needed,  and  to  withhold  it  at  will.  The  soils 
of  arid  regions  are  apt  to  be  better  supplied  with  the  mineral 
plant  foods  which  have  not  been  leached  out  by  excessive 
rains,  and  the  great  promoter  of  life  and  growth,  sunlight,  is 
more  intense  and  constant  in  an  arid  than  in  a  humid  region. 
If  sufficient  care  and  skill  be  applied  to  secure  the  full  benefit 
of  these  important  advantages,  the  acreage  yields  under  irriga- 
tion may  be  made  far  larger  than  under  natural  precipitation. 

History. — Agriculture  by  irrigation  antedates  recorded  his- 
tory, and  is  probably  one  of  the  oldest  occupations  of  civilized 
man;  but  the  time  and  place  of  its  origin  are  unknown.  Vari- 
ous countries  in  Asia,  Africa,  Europe  and  America  exhibit 
evidences  of  ancient  irrigation  works  of  prehistoric  origin  and 
unknown  antiquity. 

The  earliest  records  of  Assyria,  Babylon,  Egypt,  Persia, 
India,  China,  and  practically  every  country  of  antiquity,  bear 
testimony  to  ancient  and  well- developed  practices  of  irrigation. 

At  the  time  of  the  Spanish  conquests  in  America,  extensive 
and  well-built  irrigation  systems  existed,  antedating  the  earliest 
traditions  of  the  peoples  using  them.  Traces  of  such  works 
were  found  not  only  in  South  and  Central  America,  but  also  in 
Southern  Arizona,  New  Mexico,  Colorado,  and  California. 

As  a  modern  activity  of  the  Anglo-Saxon  race,  irrigation 
in  the  United  States  seems  to  have  had  its  origin  in  the  Salt 
Lake  Valley  of  Utah  about  the  middle  of  the  Nineteenth  Cen- 
tury at  the  present  location  of  the  city  of  Salt  Lake.  The  early 
settlers  of  California,  Arizona  and  New  Mexico  extended  the 
previous  practices  of  the  Spaniards  and  Indians  in  those  States. 


HISTORY  3 

During  the  early  history  of  American  irrigation  farmers  and 
groups  of  farmers  naturally  confined  their  efforts  mainly  to 
diverting  small  streams  upon  adjacent  valleys,  where  the  slope 
of  the  country  and  the  topography  was  such  as  to  make  the  work 
easy  and  cheap.  With  the  values  of  western  land  then  existing 
no  expensive  enterprise  was  practicable.  Such  development 
proceeding  for  nearly  half  a  century,  widely  distributed  over 
the  arid  region,  irrigated  in  the  aggregate  a  large  area  of  land. 
The  farmers  employed  the  cheapest  class  of  construction  and 
seldom  counted  their  own  time  in  computing  costs,  which  are 
hence  reported  very  low. 

As  land  values  increased  and  the  easier  projects  had  been 
developed  more  and  more  difficult  ones  were  taken  up,  sometimes 
successfully  and  sometimes  not.  As  the  more  difficult  problems 
were  attacked,  corporate  capital  and  the  district  system  were 
employed  and  such  projects  as  they  could  handle  were  gradually 
developed.  The  inherent  difficulties,  however,  did  not  admit 
of  much  profit  to  the  investor.  In  fact,  in  a  majority  of  the 
cases,  the  investors  lost  a  large  part  of  their  capital,,  to  say 
nothing  of  interest  and  profits,  and  though  the  general  benefits 
in  the  development  of  the  country  were  great  and  lasting, 
the  losses  made  it  more  and  more  difficult  to  enlist  capital  in 
further  irrigation  enterprise. 

Various  National  laws  were  passed  from  time  to  time  to 
encourage  the  irrigation  of  arid  lands,  the  Desert-Land  Act 
and  the  Carey  Act,  with  their  various  modifications,  being  the 
most  conspicuous  examples,  but  all  depending  upon  the  invest- 
ment of  private  or  corporate  capital  for  actual  construction. 
A  great  deal  was  accomplished  under  these  acts  in  spite  of  the 
great  and  growing  difficulties. 

The  increasing  difficulty  of  carrying  out  many  large  projects 
led  to  the  passage  in  1902  of  the  Reclamation  Act,  with  the 
avowed  object  of  enlisting  National  funds  for  the  development 
of  projects  not  feasible  by  private,  corporate,  district,  or  State 
enterprise. 

The  acts  provided  for  the  segregation  in  a  special  fund  of  the 
receipts  from  the  sale  of  public  lands  in  the  sixteen  Western 


4  INTRODUCTION 

States,  and  the  investment  of  this  fund  in  irrigation  works,  to 
be  returned  by  the  beneficiaries  in  small  installments.  Under 
the  operations  of  this  act  more  than  a  million  acres  have  be.en 
irrigated,  the  reclamation  of  which  would  not  have  been  feasible 
for  private  enterprise  for  a  long  time  if  ever. 

Extent  of  Irrigation. — The  total  area  irrigated  in  various 
countries  is  estimated  as  follows: 

France 6,000,000 

India  40,700,000 

Italy 3,460,000 

Russian  Empire 8,000,000 

Java 3,000,000 

Egypt 5,350,000 

Japan 7,000,000 

Philippines 130,000 

Australia 450,000 

Canada  400,000 

Hawaii 200,000 

Argentina  i  ,000,000 

Peru 640,000 

Siam i  ,750,000 

United  States 15,000,000 

Total 93,080,000 

In  addition  there  are  millions  of  acres  irrigated  in  China 
Algeria  and  other  countries,  probably  increasing  the  total  to 
nearly  100,000,000  acres. 

Returns  of  Irrigation. — The  returns  of  irrigation  vary  greatly 
with  the  soil,  climate,  degree  of  aridity,  and  the  nature  and 
value  of  the  crops  which  can  be  grown.  Thus  in  the  semi- 
humid  and  humid  regions  irrigation  may  serve  only  as  an 
insurance  on  the  crops  by  providing  against  possible  deficiencies 
in  rainfall.  In  Utah  and  neighboring  States  where  only  grain, 
hay,  potatoes,  and  kindred  crops  can  be  grown,  and  water  is  not 
economically  handled,  the  returns  from  irrigation  are  far  less 
than  in  southern  California  and  Arizona,  where  valuable  citrus 
fruits  can  be  cultivated. 


MALARIAL  EFFECTS  OF  IRRIGATION  5 

Irrigation  adds  to  the  general  wealth  of  the  country  by  in- 
creasing the  amount  of  its  agricultural  products.  It  results  in 
the  conversion  of  barren  and  desert  lands  into  delightful  homes, 
and  aids  in  the  general  development  of  the  other  resources  of 
the  region  in  which  it  is  practiced,  as  mining,  lumbering,  graz- 
ing, etc.  One  of  the  great  advantages  of  irrigation  is  that  it 
becomes  practically  an  insurance  on  the  production  of  crops. 
Its  practice  may  not  be  necessary  in  the  semi-humid  or  humid 
regions,  but  even  there  occasional  drouths  occur  and  crops 
are  lost.  Where  an  irrigation  system  exists  in  such  cases, 
it  may  be  called  into  requisition  once  or  twice  in  the  course  of 
the  year,  and  may  save  vast  sums  which  would  otherwise  be 
lost  by  the  destruction  of  crops. 

Malarial  Effects  of  Irrigation. — In  some  localities,  irrigation 
has  been  denounced  as  a  menace  to  the  health  of  the  community 
because  of  the  creation  of  swamps  and  their  malarial  effects. 
From  careful  researches,  both  by  a  committee  to  the  Indian 
Government  and  by  Dr.  H.  O.  Orme  of  the  California  State 
Board  of  Health,  it  appears  that  these  evil  effects  have  been 
exaggerated,  and  may  be  avoided  by  more  sparing  use  of  water 
and  by  proper  drainage.  Where  the  natural  drainage  is  of 
the  best,  the  soil  sandy  or  gravelly  and  open  to  a  great  depth, 
the  water  used  in  irrigation  sinks  into  the  ground  or  drains 
off,  and  the  use  of  irrigation  water  does  not  breed  malarial 
mosquitoes.  On  the  other  hand,  in  low-lying,  comparatively 
level  lands  where  the  soil  is  heavy,  the  slopes  slight,  and  the 
underdrainage  poor,  it  is  undoubtedly  true  that  irrigation 
has  developed  various  disorders,  by  raising  the  subsurface 
water-plane,  thus  causing  the  water  to  stand  in  swamps  or 
stagnant  pools,  breeding  malarial  mosquitoes. 

Malarial  effects  are  not  attributable  directly  to  the  results 
of  irrigation  where  economically  and  properly  practiced,  but 
are  frequently  due  to  carelessly  constructed  canal  works  having 
intercepted  the  natural  drainage,  thus  forming  swampy  tracts. 
When  care  is  taken  to  irrigate  economically  land  which  has 
such  slopes  and  natural  drainage  as  to  prevent  waterlogging, 
no  injurious  effects  will  result  from  irrigation;  furthermore 


6  INTRODUCTION 

when  malarial  influences  are  developed  by  irrigation  their  effect 
is  local,  and  can  be  corrected  by  drainage. 

If  wholesome  water  and  not  open-ditch  water  be  provided 
for  domestic  uses,  prejudicial  effects  of  irrigation  are  largely 
averted.  In  such  climates  as  will  encourage  its  growth  it 
appears  that  the  Eucalyptus  globulus  has  proved  beneficial 
in  mitigating  the  malarial  effects  of  irrigation  waters,  chiefly 
because  of  the  great  absorbing  and  transpiring  power  due  to 
its  rapid  growth.  The  destruction  of  mosquito  larvae  will  en- 
tirely remove  the  source  of  malarial  disorders. 

REFERENCES  FOR  CHAPTER  I 

FORTIER,  SAMUEL.     Use  of  Water   in  Irrigation.     McGraw-Hill   Book  Co.,  New 

York. 
WIDTSOE,    JOHN   A.     Principles    of    Irrigation    Practice.     Macmillan    Company, 

New  York. 
WILSON,  H.  M.     Irrigation  in  India,  1 2th  Ann.  Report  U.  S.  Geological  Survey, 

Washington. 
JAMES,   GEORGE  WHARTON.     Reclaiming  the  Arid  West.     Dodd,  Mead  &  Co., 

New  York. 

HENNY,  D.  C.     Federal  vs.  Private  Irrigation.     Engineering  News,  Jan.  15,  1915. 
NEWELL,  F.  H.     The  Human    Side  of  Irrigation.     Engineering  Record,   August 

29,  1914. 


CHAPTER   II 
SOILS 

ARABLE  soils  may  be  divided  into  four  general  classes  with 
respect  to  their  origin: 

(i)  Residual;    (2)  Alluvial;    (3)  Eolian;   and  (4)  Glacial. 

1.  Residual  soils  are  the  product  of  the  disintegration  of 
rock  in  place  under  the  action  of  air,  moisture,  frost  and  vegeta- 
tion, all  of  which  act  upon  most  natural  rocks.     As  moisture 
and  vegetation  are  most  abundant  in  humid  regions,  residual 
soils  are  there  most  general  in  consequence. 

2.  Alluvial  soils  are  the  deposits  of  sedimentation  in  bodies 
of  still  water,  and  of  flowing  streams  upon  their  banks  by  over- 
flow, and  by  the  accumulation  of  sediments  in  deltas  at  and 
near  their  mouths. 

3.  Eolian   soils   are   those  which  have  been  deposited   by 
wind  action,  and  are  common  in  the  neighborhood  of  broad 
shallow  streams  or  lakes,  whose  fluctuating  waters  leave  broad 
bare  stretches  frequently  exposed  to  wind  action  which  removes 
and  redeposits  the  surface  with  a  sorting  result,  different  from 
that  of  water. 

4.  Glacial  soils  are  the  deposits  by  glaciers  of  the  products 
of  glacial  erosion  and  some  other  agencies. 

.All  these  classes  differ  widely  in  the  methods  and  results 
of  the  mixing  process,  but  many  soils  are  the  products  of  two  or 
more  of  the  agencies  mentioned,  and  the  original  condition  of 
the  soil  is  generally  modified  superficially  by  the  action  of  wind 
and  rain. 

rThere  are  generally  certain  important  differences  between 
the  soils  of  arid  and  humid  regions,  due  to  the  difference  of 
humidity.  In  humid  regions  the  abundance  of  moisture  tends 
to  leach  out  the  more  soluble  constituents  of  the  soil,'\  and  the 


8  SOILS 

same  cause  promotes  the  luxuriant  growth  of  vegetation,  so 
that  the  tendency  is  to  remoye  the  soluble  minerals,  and  to 
accumulate  vegetable  mold.  ( As  most  alkaline  minerals  are 
highly  soluble,  and  are  hence  easily  leached  out  of  the  soils 
of  humid  regions,  and  as  the  decay  of  vegetation  produces 
certain  organic  ^acids,  there  is  often  a  resulting  acidity  of  soil 
in  humid  regions.  \ 

In  arid  regions,  on  the  contrary,  the  lack  of  moisture  leaves 
the  soluble  minerals  largely  in  the  soiLj  These-soils  are  therefore 
likely  to  contain  much  larger  percentages  of  the  various  salts 
of  potassium,  sodium,  and  magnesium,  as  well  as  the  less  soluble 
phosphates,  most  of  which  are  valuable  plant  foods. 

The  arid  condition  being  unfavorable  to  vegetable  growth, 
the  arid  soils  are  generally  deficient  in  vegetable  mold,  or  humus, 
and  sometimes  this  must  be  supplied  before  the  soil  becomes 
fer tile. -j-Most_aJka;Kne_saJjts. are  soluble  in  water,  and  therefore 
these  occur  more  generally  in  arid  than  in  humid  regions,  and 
the  soils  of  arid  regions  are  more  likely  to  be  alkaline  than 
acidjjand  the  alkalies  are  sometimes  present  to  an  extent  injuri- 
ous to  vegetation ;  an  excess  of  the  salts  of  sodium  being  especially 
harmful. 

5.  Injurious  Salts,  or  Alkali. — While  the  aridity  of  western 
soils  has  its  advantages  in  retaining  the  soluble  salts  in  the  soil, 
and  thus  preserving  the  plant  foods,  it  sometimes  happens 
that  one  or  more  soluble  elements  occurs  in  such  abundance 
as  to  be  injurious  to  vegetation.  This  is  most  important  in  the 
case  of  some  of  the  so-called  alkaline  salts,  as  the  carbonate, 
chloride  and  sulphate  of  sodium,  and  a  few  other  salts  less 
abundant  and  harmful. 

Alkalies  found  in  natural  soils  are  usually  composed  of  a 
variety  of  salts,  which  possess  widely  different  properties  with 
relation  to  plant  life. 

The  most  harmful  alkali,  and  the  one  which  becomes  harm- 
ful with  the  least  quantity  is  carbonate  of  sodium,  Na2COs. 
This  has  caustic  qualities,  and  in  the  presence  of  organic  mat- 
ter takes  on  a  dark  brown  color,  from  which  it  is  often  called 
"  black  alkali." 


INJURIOUS  SALTS,  OR  ALKALI 


9 


Where  the  carbonates  predominate,  the  presence  of  an 
average  of  one-tenth  of  one  per  cent  of  alkali  in  the  root  zone 
of  any  soil  is  disastrous  to  the  growth  of  most  useful  crops, 
and  for  the  best  results  the  quantity  should  be  much  less.  A 
somewhat  greater  quantity  of  chlorides  and  a  still  greater  per- 
centage of  sulphates  can  be  tolerated. 

In  general  a  soil  having  less  than  five-hundredths  of  one  per 
cent  oi  soluble  salts  is  acceptable,  and  one  having  more  than 
five-tenths  of  one  per  cent  of  soluble  salts  is  infertile.  Between 
these  limits,  the  fertility  depends  mainly  upon  the  character 
of  the  salts  and  of  the  soil. 

Lyon  and  Fippin  have  compiled  from  analyses  made  by 
the  U.  S.  Bureau  of  Soils,  the  following  percentage  composition 
of  Various  Natural  Soils: 

TABLE  I 


YAKIMA  VALLEY,  WASH., 

BOISE  VALLEY, 

GREAT  FORKF 

BILLINGS, 

MEADOW    LAND 

IDAHO 

N.  DAKOTA 

MONTANA 

Sur 

Surface 

Second 

Third 

Surface 

Surface 

Alkali 

12-36 

Crust 

face 

foot 

foot 

foot 

foot 

Deposit 

Crust 

ins. 

i  in. 

KC1  

5-6 

7-8 

8.1 

1.8 

1.8 

5-5 

K2SO4 

I    6 

21   4 

K2C03  

8.7 

9-7 

8.6 

Na2SO4.  ..  . 

16.5 

67.? 



85-6 

35-1 

Na2C03.  .  .  . 

66.9 

13-9 

6.6 

41-6 

.  I 

trace 

7-3 

NaCl  

17.6 

26.2 

.6 

trace 

MgSCV... 

.8 

6.2 

41-5 

24-3 

8.9 

4-i 

MgCl2  

13-3 



9.2 

8.8 



CaCl2 

I    O 

NaHC03... 

36.7 

45-3 

3i-3 

.7 

i-5 

4-3 

•  7 

22.1 

CaSO4  

9.1 

1.9 

6.2 

.6 

5-9 

19.8 

57-i 

2.7 

10.  I 

Ca(HCO3)-> 

16  ^ 

I  -2    2 

Mg(HC03)2 

12.6 

12.3 

KHCO3 

i   i 

DeVries  has  shown  that  the  presence  of  large  amounts  of 
salts  dissolved  in  the  water  in  contact  with  the  roots  of  plants 
causes  a  shrinkage  of  the  lining  of  the  cells  which,  if  persistent, 
causes  the  plant  to  wither  and  die.  In  addition  to  this,  the  car- 


10  SOILS 

bonates  of  the  alkalies  have  a  corroding  effect  directly  upon  the 
plant  tissues.  An  excess  of  alkaline  salts  sometimes  encourages 
various  plant  diseases,  and  reduces  the  efficiency  of  tillage. 

The  various  crops  are  differently  affected  by  the  presence  of 
alkali.  Some  native  grasses,  as  salt  grass  and  sacaton,  are 
the  most  resistant,  and  of  the  cultivated  grasses,  timothy  and 
alfalfa  are  the  most  tolerant.  Of  the  cereals,  barley  is  the 
most  tolerant,  and  oats  next.  Sugar  beets  are  more  tolerant 
of  alkali  than  most  other  root  crops  and  cereals. 

The  point  at  which  alkalies  become  injurious  is  indefinite, 
and  varies  not  only  with  the  crop,  but  still  more  with  the  char- 
acter of  the  salt,  the  character  of  the  soil  and  the  presence  of 
moisture.  When  the  water  content  of  the  soil  is  large  the 
dilution  of  the  salt  has  an  ameliorating  effect,  and  as  the  soil 
dries  out  the  solution  becomes  more  concentrated,  and  hence 
more  injurious.  Clay  and  loam  soils,  by  reason  of  their  greater 
water-holding  qualities,  may  carry  more  alkali  without  injury 
to  plants  than  a  sandy  one. 

In  general  the  salts  of  sodium  are  more  injurious  than  others, 
carbonates  are  more  injurious  than  chlorides,  and  chlorides  are 
more  injurious  than  sulphates.  Potassium,  calcium  and  phos- 
phorus are  all  valuable  plant  foods,  and  it  is  seldom  that  salts 
of  these  elements  are  present  in  quantities  injurious  to  vegetation. 

Alkali  is  injurious  of  course  only  when  it  is  in  close  contact 
with  the  tissues  of  the  plant,  that  is  when  present  in  the  root 
zone.  The  salts  outside  the  root  zone  are  harmless  so  long 
as  they  remain  there.  An  excellent  fertile  soil  containing  a 
small  percentage  of  alkaline  salts  may  be  ruined  by  the  con- 
centration of  salts  in  the  surface  layers  of  soil  by  the  prolonged 
upward  movement  of  water  carrying  the  salts  in  solution  and 
its  evaporation  from  the  surface.  Wherever  the  water  table 
is  raised  by  percolation  from  higher  lands  and  brought  within 
a  few  feet  of  the  surface  capillarity  does  the  rest,  by  establish- 
ing an  upward  movement  from  the  water  table  to  supply  the 
draft  of  evaporation,  and  whatever  salts  the  soil  contains  are 
carried  to  the  surface  in  solution,  and  left  there  as  the  water 
evaporates.  This  concentration  at  the  surface  may  be  fatal 


INJURIOUS  SALTS,  OR  ALKALI  11 

to  young  plants  whose  roots  are  very  delicate  and  are  near  the 
surface,  while  older  plants  of  the  same  variety  may  not  be 
injured  because  their  roots  are  deeper  where  the  salts  are  less 
concentrated,  and  because  the  older  plants  are  more  vigorous. 

On  the  other  hand,  the  rising  water  table  may  injure  deep- 
rooted  plants  before  the  salts  are  sufficiently  concentrated  at  the 
surface  to  Injure  those  of  shallow  roots,  and  thus  for  a  time  a 
high  water  table  may  be  fatal  to  alfalfa,  while  the  cereals  thrive 
on  the  same  ground.  This  condition  is  usually  temporary, 
however,  as  the  tendency  of  a  very  high  water  table  is  to  accumu- 
late soluble  salts  near  the  surface. 

On  account  of  the  wide  variety  of  possible  conditions  affect- 
ing results  it  is  impossible  to  lay  down  exact  rules  governing 
the  amount  of  alkali  that  is  injurious  to  vegetation.  This  varies 
with  the  salt  and  the  infinite  combinations  of  salts,  with  the 
crop,  with  the  character  of  soil,  with  the  moisture  conditions, 
and  with  some  minor  circumstances.  Any  rule  must  therefore 
be  regarded  as  only  a  general  indication,  and  not  an  accurate 
guide.  The  following  may  be  taken  as  rough  limits: 

Sodium  carbonate,  Na2CO3 o.i  per  cent 

Sodium  chloride,  NaCl 0.5     "     " 

Sodium  sulphate,  Na2SO4 i.o    "     " 

If  any  of  these  salts  exceed  these  limits  some  of  the  ordinary 
crops  will  be  injured  and  the  soil  is  unsuitable  for  fruit. 

Resistance  to  Alkali. — The  investigations  of  Loughridge  and 
others  indicate  relative  alkali  resistance  of  common  crops 
roughly  in  the  following  order: 

1.  Salt  grass  10.  Barley 

2.  Salt  bush  n.  Radish 

3.  Date  palm  12.  Sunflower 

4.  Modiola  13.  Bean 

5.  Sorghum  14.  Pea 

6.  Sugar  beets  15.  Grape 

7.  Hairy  vetch  16.  Artichoke 

8.  Kafir  corn  17.  Olive 

9.  Alfalfa  (old)  18.  Gluten  Wheat 


12  SOILS 

19.  Carrot  30.  Onion 

20.  Wheat  31.  Pear 

21.  Orange  32.  Goats'  rue 

22.  Celery  33.  Canaigre 

23.  Almond  34.  Mulberry 

24.  Lupine  35.  Prune 

25.  Rye  36.  Peach 

26.  Oats  37.  Apple 

27.  Fig  38.  Apricot 

28.  Alfalfa  (young)  39.  Lemon 

29.  Potato 

6.  Remedies  for  Alkali.1 — Where  a  field  once  fertile  has  been 
made  sterile  by  the  rise  of  ground  water,  bringing  alkaline 
salts  to  the  surface,  there  is  no  effectual  remedy  except  to  lower 
the  ground  water  by  means  of  deep  drains. 

a.  Leaching, — If  the  condition  is  of  long  standing  the  alkali 
may  have  accumulated  in  the  upper  layers  of  the  soil  to  such 
an  extent  that  the  land  remains  infertile  after  the  water  table 
has  been  lowered.  Indeed  the  ground  may  then  become  still 
more  sterile,  and  plants  growing  thereon  may  die,  since,  as  we 
have  already  seen,  a  given  percentage  of  alkali  in  the  soil  is  less 
harmful  with  abundance  of  water  than  under  conditions  of  less 
moisture.  In  such  cases  the  soil  must  be  leached  of  its  super- 
fluous salts.  This  is  accomplished  by  first  providing  adequate 
under  drainage,  and  following  this  with  copious  irrigation, 
keeping  the  surface  layers  of  soil  saturated  with  water  for 
protracted  periods,  so  that  there  is  a  continuous  downward 
movement  of  gravity  water  which  escapes  through  the  drains. 
-If  this  process  is  continued  long  enough  it  will  effectually  and 
permanently  remove  the  superfluous  salts,  and  of^  course  much 
plant  food  at  the  same  time. 

The  time  required  will  depend  upon  the  freedom  with  which 
the  water  passes  through  the  soil,  the  amount  of  salt  to  be 
removed,  and  some  minor  conditions,  so  that  no  rule  can  be  given, 
but  this  should  not  consume  more  than  one  year,  and  under 
some  conditions,  it  may  be  possible  to  produce  some  shallow- 
rooted  crop  at  the  same  time. 


REMEDIES  FOR  ALKALI  13 

Once  the  salts  are  removed  to  a  sufficient  extent,  one  or  two 
years  may  be  required  to  bring  the  soil  to  its  original  condition 
of  fertility.  The  water-logged  condition  and  also  the  presence 
of  alkali  operate  to  destroy  the  bacterial  activities  upon  which 
the  formation  of  plant  food  depends,  and  time  and  tillage  are 
required  to  restore  them. 

b.  Plowing. — Where  soil  containing  only  a  moderate  amount 
of  alkali  has,  through  bad  tillage,  had  this  accumulated  at  the 
surface  to  an  injurious  extent,  advantage  may  be  derived  from 
deep  plowing,  so  as  to  bring  fresh  soil  without  excessive  alkali 
to  the  surface  for  the  roots  of  the  young  plants,  which  will  be 
more  vigorous  and  resistant  by  the  time  the  roots  reach  the 
alkali  that  has  been  turned  under. 

c.  Growth  of  Suitable  Plants. — Another  practice  from  which 
benefit  may  be  obtained  where  the  excess  of  alkali  is  not  great 
is  to  plant  crops  that  are  tolerant  of  alkali  and  consume  or  ab- 
sorb a  considerable  amount  of  it,   and  by   repeated   cropping 
gradually  remove  excess  alkali  from  the  root  zone.    One  of  the 
most  effective  plants  which  can  be  grown  on  slightly  alkaline 
soil  is  alfalfa,  which  when  once  established  brings  to  bear  the 
action  of   deep  roots  and  dense  shade,  and  thus  by  repression 
of  surface  evaporation  tends  to  restore  the  soil  to  its  natural 
condition.      Where    mulching    is    practiced     it    is    desirable 
to    grow   hoed   crops,   such    as   beans,   beets,    potatoes,    corn, 
onions,  and  canaigre,  choosing  preferably  the  deeper-rooted  of 
these. 

Experiments  recently  conducted  by  Mr.  M.  E.  Jaffa  indi- 
cate that  Australian  salt-bush  is  likely  to  prove  one  of  the  most 
desirable  forage  plants  for  growth  on  alkali  soils.  It  is  readily 
eaten  by  stock,  is  nutritious,  and  has  been  successfully  grown 
on  alkaline  land  which  will  produce  no  other  crop.  This  plant 
is  remarkable  for  its  productiveness  and  its  drouth-resisting 
power.  It  is  prostrate  in  its  growth,  covering  the  ground  with  a 
green  cushion  8  to  10  inches  thick,  and  thus  effectually  shading 
it.  It  is  perennial,  and  when  cut  soon  reproduces  itself  from 
the  same  root.  Its  yield  per  acre  is  very  large,  being  about 
the  same  as  that  of  alfalfa. 


14  SOILS 

d.  Mulching. — An  excellent  preventive  against  evaporation 
from   the   soil   surface    and    the    consequent    rise    of    alkali    is 
"  mulching."     A  good  mulch  is  a  well  and  deep-tilled  surface 
soil,  which  is  kept  so  constantly  stirred  that  a  crust  is  never 
allowed  to  form.     As  a  result  evaporation  is  reduced  to  a  mini- 
mum, and  the  alkali  remains  distributed  throughout  the  whole 
of  the  tilled  layer  instead  of  as  a  hard  crust  at  the  surface 
where  the  bulk  of  the  damage  is  done.     Large  quantities  of  straw 
produces  also  an  effective  mulch,  since  the  straw  keeps  the  sur- 
face moist  and  enables  the  grain  to  germinate.     The  depth 
or  thickness  of  this  protective  layer  is  of  the  utmost  importance 
for   thereby   the   surface   evaporation  is   diminished.     After   a 
proper  plowing  to  a  depth  of,  say,  10  to  12  inches,  it  requires 
a  long  time  for  the  salts  to  come  to  the  surface  again  in  suffi- 
cient amount  to  injure  the  crop. 

e.  Gypsum. — Where  the  alkali  is   mainly  carbonate  of  soda, 
much  benefit  may  be  derived  by  the  application  of  ground 
gypsum   or   sulphate   of   calcium.     This   must   be    thoroughly 
mixed  with  the  soil,  and  the  two  salts  mingling  in  solution  in 
the  same  water,  in  obedience  to  an  elementary  chemical  prin- 
ciple, perform  the  following  reaction: 

Na2C03 + CaS04  =  Na2S04 + CaC03. 

Forming  Sodium  Sulphate  and  Calcium  Carbonate.  The  latter 
is  only  slightly  soluble  in  water,  and  is  harmless.  The  sodium 
is  transformed  into  sulphate  which  is  far  less  harmful  than  the 
carbonate,  and  is  more  easily  removed  by  drainage. 

Experiments  have  been  made  by  Prof.  E.  W.  Hilgard  which 
prove  the  value  of  gypsum  in  neutralizing  the  "  black  alkali," 
or  carbonate  of  soda.  In  the  case  of  this  alkali  mulching,  deep 
tillage,  suitable  plant-growth,  or  any  other  corrective  except 
gypsum  is  practically  unavailing.  Little  benefit  is  to  be  expected 
from  gypsum  in  the  case  of  "  white  "  or  neutral  alkali,  which 
does  little  harm,  however,  under  proper  tillage;  but  a  soil 
heavily  tainted  with  black  alkali  can  be  rendered  productive 
by  the  use  of  a  ton  of  gypsum  per  acre.  This  is  more  effective 
when  applied  at  the  rate  of  about  500  pounds  per  acre  per 


REMEDIES  FOR  ALKALI  15 

annum  in  connection  with  some  seeding  at  the  same  time, 
for  the  slightest  growth  aids  in  shading  the  ground  and  pre- 
venting an  injurious  release  of  salts  by  evaporation.  Gypsum, 
however,  cannot  be  used  on  alkali  without  water;  its  action  must 
be  continued  for  several  months  and  through  two  or  three  seasons ; 
it  takes,  moreover,  several  weeks  before  immunity  is  secured, 
and  therefore  the  dressing  of  gypsum  should  be  applied  in 
ample  time  before  the  seeding;  and  thereafter  the  soil  must  be 
well  cultivated  the  gypsum  plowed  in,  and  water  promptly 
applied. 

The  sovereign  preventive  and  cure  for  alkali  of  any  kind, 
however  caused,  is  deep  drainage,  supplemented  if  necessary 
by  copious  surface  irrigation,  to  produce  a  downward  move- 
ment of  water  from  the  surface  to  the  drain. 

Where  alkali  is  accumulated  at  or  near  the  surface,  efforts 
are  sometimes  made  to  remove  it  by  heavy  applications  of 
water,  drained  off  by  surface  drains.  Such  efforts  seldom  yield 
perceptible  benefit,  as  the  water  that  actually  comes  in  contact 
with  the  salt,  enters  the  soil  and  remains  there  or  passes  down- 
ward, while  that  which  runs  off  the  surface  carries  very  little 
salt. 

REFERENCES  FOR  CHAPTER  II 

BARK,  DON  H.     Duty  of  Water  Investigation  in  Idaho.     8th  and  pth  Biennial 

Reports,  State  Engineer  of  Idaho,  Boise,  Ida.,  1910-12. 
KING,  F.  H.     Irrigation  and  Drainage.    Macmillan  Company,  New  York. 
ETCHEVERRY,  B.  A.     Use  of  Irrigation  Water.     McGraw-Hill  Book  Company,  New 

York. 

HILGARD,  E.  W.  Soils.  Macmillan  Company,  New  York. 
LYON  &  PIPPIN.  Soils.  Macmillan  Company,  New  York 
WIDTSOE,  J.  A.  Principles  of  Irrigation  Practice.  Macmillan  Company,  New 

York. 
LOUGHRIDGE,  R.  H.     Distribution  of  Water  in  the  Soil  in   Furrow  Irrigation. 

Office  of  Experiment  Stations,  Bulletin  No.  203. 


CHAPTER   III 
SOIL  MOISTURE 

MOST  soils  in  humid  regions,  and  many  in  arid  regions 
especially  where  irrigated,  are  permanently  saturated  with 
water  at  certain  depths,  and  the  surface  of  the  saturated  mass 
is  called  the  "  water  table  "  or  the  surface  of  "  ground  water." 

1.  Free    Water. — When    a    soil    saturated    with    water     is 
provided  with  perfect  drainage,  a  portion  of  the  water  will  be 
drawn  off  by  the  action  of  gravity,  and  replaced  by  air.     This 
water  may  be   called   "  Free   Water,"   or   "  Gravity  Water." 

2.  Capillary  Water.— The  soil  thus  drained  will  still  remain 
moist,  a  considerable  quantity  of  water  being  held  by  capillary 
attraction  in  the  finer  pore  spaces,  and  as  films  on  the  particles 
of   the   soil.     This  is  called  ''capillary  "  water;    and  varies  in 
percentage  with  the  fineness  of  the  soil,  being  more  abundant 
in  clay  and  loam  than  in  sandy  soils.     The  space  vacated  by  the 
gravity  water  is  at  once  occupied  by  air,  so  that  with  the  gravity 
water  withdrawn  and  the  capillary  water  remaining  the  soil 
is  well  supplied  with  both  air  and  water,  which  is  a  favorable 
condition   for   the  growth   of   ordinary  plants.     The  capillary 
water  is  gradually  taken  up  by  plants  or  evaporated,  and  unless 
a  new  supply  is  furnished,  the  soil  becomes  what  we  call  "  dry," 
and  the  plants  wilt  and  die  for  lack  of  moisture. 

3.  Hygroscopic   Water. — After   the  soil  has  been  as   thor- 
roughly  dried  as  possible  without  the  application  of  artificial 
heat,  it  still  retains  some  water,  called  "  hygroscopic  water  " 
that  may  be  driven  off  by  a  protracted  application  of  heat, 
after  which  the  soil,  when  exposed  to  a  moist  atmosphere,  will 
reabsorb  an  equal  quantity  of  water  and  still  appear  dry,  and  in 
fact  actually  be  dry  so  far  as  plant  needs  are  concerned.     The 
hygroscopic  moisture  in  soils  varies  with  its   texture,   from    i 

16 


CAPILLARY  MOVEMENT  17 

per  cent  in  coarse  sand  to  nearly  10  per  cent  in  clay,  and  still 
more  when  certain  salts  are  present.  It  is  not  available  for  plant 
consumption  and  is  properly  disregarded  in  considering  irriga- 
tion needs.  The  soil  must  receive  an  appreciable  addition  of 
water  usually  over  50  per  cent  above  its  content  of  hygroscopic 
water,  before  any  becomes  practically  available  for  plant  use, 
and  every  addition  above  this  point  makes  it  more  and  more 
easily  available;  that  is,  it  is  more  loosely  held  by  the  soil 
particle,  until  a  plenitude  of  moisture  is  reached  called  the 
"  maximum  capillary  capacity,"  after  which  additional  water 
flows  off  the  soil  particles  under  the  action  of  gravity  and 
drops  to  lower  levels  or  drier  soil,  or  passes  down  to  the  water 
table,  as  gravity  water. 

The  capacity  for  holding  capillary  water  varies  with  the 
density  of  the  soil,  from  about  12  per  cent  for  coarse  sand  to 
20  per  cent  for  very  heavy  clay,  averaging  about  16  per  cent 
for  loam. 

The  amount  of  capillary  water  held  by  the  soil  particle 
before  it  becomes  practically  available  for  plant  consumption 
must  exceed  i  per  cent  for  coarse  sand,  2  per  cent  for  fine  sand, 
3  per  cent  for  sandy  loam  and  4  per  cent  and  over,  for  heavier 
loams  and  clay.  Even  at  these  percentages,  the  water  is  taken 
*by  plants  slowly  and  with  difficulty,  and  a  larger  quantity  is 
necessary  for  the  best  growing  conditions.  When  the  amount 
of  capillary  water  falls  below  these  quantities,  the  plant  begins 
to  show  signs  of  distress,  growth  ceases,  wilting  begins,  and 
permanent  injury  or  death  will  soon  ensue  unless  water  is 
supplied.  The  point  at  which  wilting  begins  in  any  given  soil 
is  called  the  wilting  coefficient  of  that  soil.  It  is  nearly  the 
same  for  all  ordinary  crops. 

4.  Capillary  Movement. — Capillary  water  moves  in  any  direc- 
tion toward  drier  soil  under  the  action  of  capillary  attraction. 
At  the  water  table  all  the  pore  spaces  of  the  soil  are  filled  with 
water.  Just  above  this  level,  the  soil  is  wet  to  its  "  capillary 
capacity,"  and  the  remainder  of  its  pore  spaces  are  filled  with 
air.  The  amount  of  capillary  water  held  by  the  soil  diminishes 
from  the  water  table  upward  at  a  rate  uniform  for  uniform  soil 


18 


SOIL  MOISTURE 


texture,  and  approximates  zero  at  a  distance  above  the  water 
table,  depending  upon  the  fineness  of  the  soil  particles,  and 
varying  from  about  i  foot  for  coarse  sand,  to  6  feet  or  over 
for  heavy  clay.  Its  motion  is  extremely  slow  in  clay,  and 
relatively  rapid  in  coarse-grained  soils. 

Lyon  and  Fippin  have  given  the  rate  and  extent  of  capillary 
movement  for  the  various  soils  shown  in  the  following  table: 

TABLE   II.— EXTENT  AND   RATE   OF   CAPILLARITY 


CAPILLARY  RISE  IN  INCHES 

Kind  of  Soil 

15 

i 

2 

i 

3 

8 

13 

19 

min. 

hr. 

hrs. 

day 

days 

days 

days 

days 

Silt  and  very  fine  sand  .  . 

2.7 

4-7 

7.0 

2O.  0 

30.0 

45-0 

52.0 

56.0 

Very  fine  sand  

7-6 

10.  0 

12.4 

21  .0 

23.0 

26.0 

27  •  5 

28.5 

Fine  sand     

9.0 

9-5 

10.  0 

ii.  6 

13-0 

14.3 

15-2 

16.0 

Coarse  and  medium  sand 

5-8 

6.0 

6-3 

7-5 

9.0 

IO.O 

n-5 

12-5 

Fine  Gravel  

4.0 

5-0 

5-3 

6.4 

8.0 

9.0 

IO.O 

10.8 

Clay  will  give  a  greater  total  rise  but  at  a  slower  rate  than 
any  of  the  above  results.  Instances  have  been  recorded  where 
water  has  risen  by  capillarity  a  total  distance  of  8  feet  through 
heavy  clay. 

Where  water  is  applied  in  irrigation,  the  soil  in  proximity 
to  the  water  is,  of  course,  immediately  saturated,  and  the 
gravity  portion  of  the  water  seeks  lower  levels,  under  the  influ- 
ence of  both  gravity  and  capillary  attraction.  This  movement 
is  rapid  in  coarse  open  soils  like  sand  or  gravel,  but  much  slower 
in  loam  or  clay.  The  wetted  soil  retains  a  sufficient  quantity 
to  satisfy  its  capillary  capacity,  and  all  the  surplus  continues 
to  sink,  filling  the  soil  to  the  capillary  capacity  as  it  goes  until 
ground  water  is  reached,  when  the  surplus  is  consumed  in  raising 
the  ground-water  table  or  passes  away  in  whatever  drainage 
channels  are  available. 

5.  Optimum  Water  Supply. — The  ideal  quantity  of  water 
for  most  rapid  plant  growth  is  that  quantity  that  will  just  fill 
the  soil  to  its  capillary  capacity  to  the  depth  occupied  or  soon 
to  be  reached  by  plant  roots,  without  affording  any  excess  to 


OPTIMUM   WATER  SUPPLY  19 

escape  to  the  ground  water  table,  or  to  the  soil  zone  below  the 
reach  of  crop  roots.  All  water  that  escapes  to  the  water  table 
and  passes  off  as  drainage  is  usually  wasted,  carries  with  it  in 
solution  more  or  less  plant  food,  and  may  contribute  to  raise 
the  water  table  and  produce  seepage  troubles.  For  these  rea- 
sons it  is  usually  better  to  stop  short  of  the  complete  capillary 
saturation  of  the  soil  in  the  root  zone  than  to  risk  the  loss  of 
water,  by  excess  application.  It  is  generally  not  possible  to 
attain  the  ideal,  for  if  the  soil  be  charged  to  its  capillary  capac- 
ity to  the  bottom  of  the  root  zone,  and  the  water  table  be  not 
reached,  the  water  will  continue  to  descend  under  the  combined 
action  of  gravity  and  capillarity,  and  thus  escape  beyond  the 
reach  of  crop  roots  and  leave  the  soil  in  the  root  zone  with  less 
than  its  full  load  of  capillary  water. 

At  the  end  of  each  irrigation,  the  upper  zone  of  the  soil  is 
saturated  to  a  considerable  depth,  and  the  gravity  water  in  this 
zone  is  slowly  descending  to  lower  levels.  Evaporation  from 
the  surface  begins  almost  immediately,  and  the  moisture  of  the 
surface  soil  is  soon  reduced  by  the  combined  process  to  a  point 
below  capillary  saturation,  and  shortly  after,  an  upward  move- 
ment begins  of  capillary  water  to  supply  the  losses  from  evap- 
oration from  the  surface.  The  zone  of  saturation  is  thus  slowly 
sinking  in  obedience  to  the  force  of  gravity,  and  is  also  being 
depleted  by  capillary  action  both  upward  and  downward,  and 
unless  an  excess  has  been  applied,  the  store  of  free  or  gravity 
water  is  soon  dissipated  and  distributed  through  the  soil  as 
capillary  water.  Thus,  after  each  irrigation,  a  condition  is 
soon  reached,  in  which  a  narrow  zone  a  short  distance  below 
the  surface  is  in  a  state  of  capillary  saturation,  and  the  per- 
centage of  moisture  diminishes  both  upward  and  downward, 
at  a  nearly  uniform  rate.  If  at  this  time  the  moisture  at  the 
lower  limit  of  the  root  zone  is  just  a  little  above  the  wilting 
coefficient,  the  water  has  been  economically  applied,  and  none 
wasted.  The  water  content  of  the  soil  decreases  gradually  from 
this  point  by  evaporation  from  the  surface,  and  by  plant  con- 
sumption and  transpiration  throughout  the  zone  occupied  by 
plant  roots. 


20  SOIL  MOISTURE 

As  the  evaporation  all  occurs  from  the  surface,  the  general 
movement  of  moisture  is  upward  soon  after  the  supply  of 
gravity  water  is  dissipated.  The  tendency  therefore  is  to 
accumulate  the  soluble  portions  of  the  soil  at  or  near  the  sur- 
face, where  the  pure  water  is  evaporated  and  the  solids  are 
left  behind.  It  is  important  that  this  tendency  be  combated 
by  retarding  evaporation  through  cultivation.  When  crops 
are  not  cultivated,  the  evaporation  from  the  surface  may  be 
nearly  as  great  as  the  consumption  of  moisture  by  the  plants, 
whereas  if  the  soil  is  kept  pulverized  to  a  considerable  depth, 
the  volume  of  water  taken  up  by  the  plants  is  5  or  6  times  as 
great  as  that  lost  by  evaporation,  which  hence  becomes  almost 
negligible,  and  has  little  tendency  to  accumulate  salts  at  the 
surface,  and  this  is  overcome  by  necessary  deep  plowing. 

Soil  which  is  as  dry  as  it  can  be  made  without  artificial 
processes  still  contains  a  considerable  amount  of  hygroscopic 
moisture  adhering  to  its  grain.  The  percentage  by  weight 
which  this  bears  to  the  weight  of  the  soil  is  called  the  hygro- 
scopic coefficient,  and  this  must  be  increased  at  least  50  per 
cent  before  it  becomes  available  for  sustaining  plant  life. 

6.  Wilting  Coefficient. — The  point  at  which  vegetation  wilts 
and  dies  for  lack  of  moisture  is  called  the  wilting  coefficient. 
The  water  available  for  plant  consumption,  therefore,  is  that 
portion  of  the  capillary  water  which  it  contains  in  excess  of  the 
wilting  coefficient.     The  water  content  of  the  soil  upon  which 
a  growing  crop  depends  must  never  fall  as  low  as  the  wilting 
coefficient,    nor    be    increased    above    the    capillary    capacity, 
except  temporarily. 

7.  Water  Required. — The  amount  of  water  required  for  a 
single  irrigation  depends  on  the  character  of  the  soil,  the  depth 
to  which  it  is  desired  to  moisten  it,  and  the  amount  of  moisture 
it  already  contains. 

Prof.  L.  J.  Briggs,  Prof.  Loughridge,  Prof.  Hilgard  and 
others  have  made  a  large  number  of  observations  upon  the 
hygroscopic  and  wilting  coefficients  of  various  soils,  and  a  large 
number  of  comparisons  of  these  are  condensed  in  the  following 
table,  which  gives  also  the  capillary  capacity,  the  available 


WATER    REQUIRED 


21 


capacity  or  difference  between  the  capillary  capacity  and  wilting 
point,  and  the  total  capacity  for  moisture  for  various  soils: 

TABLE  III.— PERCENTAGE  BY  WEIGHT  OF  MOISTURE  CAPACITIES 
FOR  VARIOUS  SOILS 


Type  of  Soil 

Hygro- 
scopic 
Coeffi- 
cient 

Wilting 
Coeffi- 
cient 

Capillary 
Capacity 

Available 
Capacity 

Total 
Capacity 

Coarse  sand      

I  .0 

1  .5 

13 

II  .5 

33 

Fine  sand 

2  .  I 

7  .  2 

14 

10.  7 

24 

Sandy  loam  
Fine  sandy  loam        .        

4-7 
6.9 

7.0 
10.8 

15 
16 

8.0 

5  •  2 

35 
37 

Loam 

0    I 

124 

18 

4.6 

38 

Clay*loam  
Clay 

n.  8 

13.2 

15-0 
16.5 

iQ 

20 

4.0 
3-5 

40 
42 

It  will  be  seen  from  the  above  that  if  a  loam  of  the  type 
above  assumed  is  dried  to  the  wilting  point,  it  still  contains 
13.4  per  cent  of  water  by  weight,  and  can  retain  by  capillarity 
4.6  per  cent  additional  water,  or  about  4  pounds  per  cubic  foot, 
and  it  would  require  about  J  cubic  foot  of  water  to  fill  a  square 
foot  of  area  to  a  depth  of  4.2  feet  to  its  full  capillary  capacity. 
Such  an  application  to  very  dry  loam  of  the  type  assumed 
would  constitute  a  good  irrigation.  That  is  it  would  require 
3  inches  in  depth  applied  to  the  land. 

Similarly,  a  sandy  loam  of  the  type  given  in  the  table  would 
require  under  the  same  circumstances  about  75  per  cent  more 
water,  or  a  depth  of  about  5J  inches;  coarse  sand  would  require 
about  7^  inches  in  depth,  and  clay  would  require  a  little  less 
than  3  inches. 

Irrigation  should  always  be  applied  before  the  soil  moisture 
reaches  the  wilting  point  throughout  the  root  zone,  otherwise 
the  plants  will  be  severely  injured  or  killed. 


CHAPTER  IV 
PLANT  FOOD 

THE  essential  mineral  elements  of  plant  food  derived  from 
the  soil  are  calcium,  potassium,  phosphorus,  magnesium,  iron 
and  sulphur.  Other  elements,  equally  important,  are  derived 
mainly  from  air,  and  water,  or  from  decayed  vegetation.  These 
are  nitrogen,  oxygen,  hydrogen  and  carbon.  Magnesium, 
iron  and  sulphur  are  used  in  very  small  amounts,  and  occur 
in  all  natural  soils  in  sufficient  quantity  to  answer  ordinary 
plant  needs,  but  most  soils  require  for  best  results  the  occasional 
artificial  addition  of  some  of  the  other  elements.  Nearly  all 
the  hydrogen,  and  most  of  the  oxygen  consumed  by  plants  is 
furnished  in  the  form  of  water  (H^O). 

i.  Functions  of  Water  in  Plant  Growth. — Water  is  the  most 
abundant  constituent  of  the  body  of  the  live  plant,  and  thus 
forms  a  most  important  element  of  the  plant's  food.  In  addi- 
tion to  this,  it  is  the  necessary  vehicle  for  carrying  in  solution 
all  the  other  elements  of  plant  food  that  are  absorbed  from  the 
soil  by  plant  roots,  and  conveyed  in  solution  to  the  various 
parts  of  the  plant  for  assimilation.  Hence  the  vital  importance 
to  the  plant  of  having  a  constant  and  sufficient  supply  of  water. 
When  the  water  has  performed  its  function  as  a  vehicle  the 
portion  not  required  for  food  by  the  plant  is  transpired  by  the 
leaves,  and  absorbed  by  the  atmosphere  in  the  form  of  watery 
vapor. 

The  amount  of  water  consumed  by  the  plant  in  forming  a 
unit  quantity  of  tissue  varies  widely  with  the  character  of 
the  plant  and  the  available  plant  food.  The  results  of  experi- 
ments to  determine  this  are  found  in  the  following  table: 

22 


MINERAL  FOODS 


23 


TABLE  IV.— POUNDS  OF  WATER  CONSUMED   BY  VARIOUS  CROPS 
IN  THE  PRODUCTION   OF   ONE  POUND   OF  DRY  MATTER 


Lawes 

and 
Gilbert 

Hellreigel 

Wollny 

King 

Widtsoe 

Average 

Wheat  

225 

359 

1006 

530 

Oats 

402 

665 

CC7 

541 

Barley  

262 

3IO 

774 

393 

.  .  . 

435 

Peas 

23S 

2Q2 

479 

447 

363 

Red  Clover  

2  49 

33° 

453 

344 

Corn  

233 

272 

387 

297 

Potatoes  

423 

1440 

93i 

Beans  

214 

262 

.  .  . 

.  .  . 

.  .  . 

238 

Buckwheat  

37i 

664 

5i8 

Sugar  Beets  

662 

662 

Alfalfa 

97° 

97° 

Average  

530 

2.  Mineral  Foods. — Since  the  plant  can  take  its  food  only 
in  liquid  form  it  follows  that  soil  particles  to  be  available  for 
plant  food  must  be  soluble  in  water.  All  the  chemical  elements 
are  to  some  extent  soluble  in  water,  but  they  differ  widely  in 
the  rapidity  of  solution,  and  the  amount  that  can  be  dissolved 
by  a  given  quantity  of  water. 

All  nitrates  and  most  combinations  of  sodium  and  potassium 
are  readily  soluble  in  water  in  considerable  quantities,  but  even 
these  are  strictly  limited  in  the  amount  that  can  be  dissolved 
in  a  given  volume  of  water,  which  is  said  to  be  "  saturated  " 
when  it  can  dissolve  no  more  of  a  given  solid.  When  such  a 
saturation  solution  is  subjected  to  evaporation,  the  water 
passes  into  the  atmosphere,  and  leaves  a  portion  of  the  dis- 
solved mineral  in  excess  of  that  which  the  remaining  water  can 
hold  in  solution,  which  is  accordingly  deposited  as  solid  crystals 
of  the  mineral  with  which  the  water  is  saturated.  At  the  same 
time  other  minerals  may  be  present  in  quantities  below  the 
point  of  saturation,  and  these  may  remain  in  solution. 

In  general,  nitrates  dissolve  in  water  rapidly  and  in  consider- 
able quantities.  Sulphates,  phosphates  and  carbonates  are 
soluble  in  less  degree,  and  silicates  still  less  so,  except  the 


24  PLANT  FOOD 

alkaline  salts,  most  of  which  are  readily  soluble.  Nitrogen  is 
a  rather  inert  element,  having  little  chemical  affinity  for  any 
other  elements.  Hence  in  nature  it  exists  almost  entirely  as  a 
free  gas  in  the  atmosphere,  uncombined  with  any  element. 
Pure  air  is  composed  of  a  mechanical  mixture  of  oxygen  and 
nitrogen  uncombined  chemically,  in  the  proportion  of  4  parts 
of  nitrogen  to  i  of  oxygen  by  weight.  The  oxygen  is  vitally 
necessary  to  animal  existence,  while  the  free  nitrogen,  though 
harmless,  is  unnecessary  except  as  a  dilutant.  This  inert 
nitrogen,  however,  when  combined  with  other  elements,  forms 
some  of  the  most  useful  and  necessary  foods,  both  plant  and 
animal,  and  in  still  other  combinations  forms  some  of  the  most 
powerful  acids  and  explosives.  It  has  a  constant  tendency  to 
revert  back  to  its  atmospheric  state,  and  hence  the  stores  of 
natural  combined  nitrogen  are  rare  and  limited.  Their  pro- 
portion of  the  solid  earth  is  negligible,  and  the  existing 
stores  of  nitrates  are  valuable  as  fertilizers  and  for  other 
uses. 

When  natural  rocks  are  disintegrated  and  broken  up  into 
fragments  and  soil  particles,  the  more  soluble  portions  are 
gradually  dissolved  by  the  rains  and  pass  off  with  the  drainage 
water.  It  thus  occurs  that  the  more  soluble  salts  of  sodium 
and  potassium  are  carried  to  the  ocean  and  held  there  in  solu- 
tion in  large  quantities,  while  the  silicates  and  other  relatively 
insoluble  rock  particles  remain  as  soil.  The  sulphates,  phos- 
phates and  carbonates  of  the  non-alkaline  metals  being  less 
soluble  than  the  alkaline  salts,  pass  away  less  rapidly,  but 
being  more  soluble  than  the  silicates  of  the  same  metals,  have  a 
constant  tendency  to  leach  out  and  leave  the  silica  and  silicates 
in  the  form  of  sand  and  clay  to  form  the  main  constituents 
of  the  soil.  The  tendency  is  thus  in  humid  regions  except  in 
swamps,  gradually  to  deprive  the  natural  soils  of  their  mineral 
plant  food,  a  tendency  existing  in  far  less  degree  in  arid  regions. 
Hence  the  soils  of  arid  regions  are  much  richer  in  mineral  plant 
food  than  most  of  those  in  humid  regions,  but  the  latter  are 
generally  better  supplied  with  nitrates,  contained  in  humus  or 
vegetable  mold. 


FERTILIZING  EFFECTS  OF  SEDIMENTS 


25 


3.  Fertilizing  Effects  of  Sediments. — The  value  of  silt-bearing 
water  as  a  fertilizer  is  well  known.  In  the  valley  of  the  Moselle, 
France,  on  land  barren  without  fertilization,  the  alluvial  matter 
deposited  by  irrigation  from  turbid  water  renders  the  soil 
capable  of  producing  two  crops  a  year.  In  the  valley  of  the 
Durance,  France,  the  turbid  waters  of  that  stream  bring  a 
price  for  irrigation  several  times  greater  than  that  paid  for  the 
clear  cold  water  of  the  Sorgues  River.  It  has  been  estimated 
that  on  the  line  of  the  Galloway  canal  in  California,  land  which 
has  been  irrigated  with  the  muddy  river  water,  gives  18  per  cent 
better  results  after  the  fifth  year  than  the  same  land  which  has 
been  irrigated  with  clear  artesian  water. 

In  the  Nile  Valley  the  turbid  waters  of  the  White  Nile  are 
recognized  as  far  more  valuable  than  the  clear  waters  of  the 
Blue  Nile,  on  account  of  the  fertility  carried  by  the  mud. 

The  fertilizing  value  of  the  silts  of  some  of  our  southwestern 
streams  is  shown  by  the  following  table,  which  compares  their 
fertilizing  contents  with  the  food  requirements  of  a  ton  of 
alfalfa: 

TABLE  V.— FERTILIZING  VALUE  OF  SEDIMENT 


PLANT  FOOD  PER  ACRE  FOOT 

OF  WATER 

River 

Date 

Phosphoric 

Potash 

Nitrogen 

Authority 

Acid  Ibs. 

Ibs. 

Ibs. 

Rio  Grande  

1893-94 

31-4 

325-5 

24.40 

Goss 

Salt  River  

1899-1900 

10-5 

26.5 

9.00 

Forbes 

Colorado,  minimum  

1900-1901 

2.26 

l6.3 

1.03 

Forbes 

Colorado,  maximum  .... 

1900-1901 

43-56 

444.6 

69.70 

Forbes 

i  ton  alfalfa  



16.7 

33-0 

42.00 

Goss 

REFERENCES  FOR  CHAPTERS  III  AND  IV 

BRIGGS,  L.  J.  and  SCHANTZ,  H.  L.    Wilting    Coefficient  for  Different  Plants. 

Bulletin  No.  230.     Bureau  of  Plant  Industry,  Washington. 
WIDTSOE,  J.   A.     Storage  of  Winter  Precipitation  in   Soils.      Utah  Exp.   Sta., 

Bulletin  No.  104. 
ETCHEVERRY,  B.  A.     Use  of  Irrigation  Water.     McGraw-Hill  Book  Company 

New  York. 


26  PLANT  FOOD 

FORTIER,  SAMUEL.     Evaporation  Losses  in  Irrigation  and  Water    Requirements 

of  Crops.     Bulletin  No.  177.     Office  of  Experiment   Stations,  Washington. 
LOUGHRIDGE,    R.    H.     Moisture    in    California    Soils.     Report    of    Agricultural 

Experiment  Station,  University  of  California,  1897-98. 
WIDTSOE,  J.  A.  and  MCLAUGHLIN,  W.  W.     Movement  of  Water  in  Irrigated 

Soils.     Utah  Experiment  Station.     Bulletin  No.  115. 
LYON  &  FIPPIN.     Soils.     Macmillan  Company,  New  York. 
BARK,  DON  H.     Alfalfa  Growing.     Address  before  Western  Canada  Irrigation 

Association.     Bassano,  Alberta,  November,  1915. 
Goss,  ARTHUR.     Principles  of  Water  Analysis  as  Applied  to  New  Mexico  Waters. 

Bulletin  No.  34.     New  Mexico  Agr.  Exp.  Station. 
FORBES,   R.   H.     The   River  Irrigating  Waters   of  Arizona.     Bulletin   No.   44. 

University  of  Arizona  Agricultural  Exp.  Station,  Tucson,  Arizona. 
FOLLETT,  W.  W.     Silt  in  the  Rio  Grande.     International  Boundary  Commission, 

Dept.  of  State. 

SWINGLE,  Z.  T.     Bulletin  No.  53.     Bureau  of  Plant  Industry. 
HILGARD,  E.  W.     Distribution  of  Salts  in  Alkali  Soils.     Bulletin  No.  108.     Univ. 

of  Cal. 

WILSON,  H.  M.     Irrigation  in  India.     Part  II  of  i2th  Annual  Report,  U.  S.  Geo- 
logical Survey. 
ETCHEVERRY,  B.  A.     Irrigation  Practice  and  Engineering.    McGraw-Hill  Book 

Company,  N.  Y, 


CHAPTER  V 
WATER   SUPPLY 

ALL  the  water  used  by  plants  is  precipitated  from  the 
atmosphere  as  rain,  snow  or  dew,  which  in  humid  regions  are 
sufficiently  regular  and  abundant  for  crop  production,  but  in 
arid  regions  are  sufficient  only  for  the  precarious  sustenance  of  a 
limited  variety  of  grasses,  shrubs  and  trees  which  have  the 
property  of  becoming  dormant  without  dying  in  times  of  drouth, 
and  reviving  and  growing  when  sufficient  moisture  comes. 

The  groups  and  ranges  of  mountains  in  arid  regions  by 
reason  of  their  superior  elevation  have  greater  precipitation 
than  the  plains  and  valleys,  and  thus  become  the  sources  of 
such  streams  as  occur,  and  the  snows  of  winter  falling  on  those 
mountains  serve  as  storage  reservoirs,  to  hold  the  moisture 
until  the  warm  days  of  spring  and  summer  melt  the  snow  and 
swell  the  streams  at  the  time  their  waters  are  needed  for  irriga- 
tion upon  the  valleys  which  they  traverse.  These  streams 
constitute  the  principal  source  of  water  used  in  irrigation. 

i.  Causes  of  Rainfall.— Although  meteorology  is  a  rather 
elusive  science,  much  progress  has  been  made  in  the  study  of 
phenomena  and  some  general  laws  regarding  the  cause  and 
distribution  of  rainfall  have  been  evolved. 

The  capacity  of  air  for  holding  water  in  the  form  of  an 
invisible  gas  is  a  function  of  its  temperature.  Warm  air  can 
retain  a  large  amount  of  moisture  without  any  tendency  of  the 
moisture  to  condense;  but  if  the  air  be  cooled  sufficiently  a 
point  will  be  reached  where  the  water  begins  to  condense,  and 
separate  as  particles  of  vapor  or  cloud.  At  this  point  the  air 
is  said  to  be.  saturated,  and  the  relative  humidity  is  100  per 
cent.  This  critical  temperature  is  called  the  dew  point.  The 
particles  of  vapor  are  very  minute,  and  they  may  float  about 

27 


28  WATER  SUPPLY 

as   clouds,   but  if   formed   rapidly   they   usually   coalesce  into 
large  drops  and  fall  as  rain. 

The  principal  causes  that  contribute  to  abundant  rainfall 
are: 

1.  Proximity  to  the  ocean  or  other  large  body  of  water. 

2.  Mountain  ranges,   especially  if   their   trend   is   at  right 
angles  to  the  direction  of  moisture-laden  winds. 

3.  Location  on  or  near  the  track  of  cyclonic  storms. 

The  North  Pacific  Coast  combines  all  three  tendencies, 
resulting  in  a  heavy  precipitation. 

The  first  condition  is  not  always  sufficient,  as  many  islands 
in  the  Pacific  Ocean  are  arid,  as  is  the  Pacific  Coast  of  Southern 
California,  Mexico  and  parts  of  South  America. 

The  greatest  rainfall  usually  occurs  in  belts  where  moist 
winds  from  large  bodies  of  water  are  forced  to  rise  and  pass 
over  mountains  which  forcibly  cool  them  and  condense  their 
moisture.  Such  conditions  are  most  pronounced  where  a  high 
mountain  range  parallels  an  adjacent  sea  coast  and  is  at  right 
angles  to  the  direction  of  the  prevailing  winds.  As  the  water- 
laden  air  rises,  the  overlying  atmosphere  becomes  less,  thus 
decreasing  pressure,  and  allowing  the  elastic  air  to  expand, 
which  in  turn  causes  rapid  cooling,  condensation  and  precipita- 
tion of  the  moisture.  If  the  mountain  range  is  high  and  exten- 
sive, the  process  is  proportionately  complete,  and  as  the  winds 
descend  the  leeward  slope  and  are  again  compressed  their 
moisture-absorbing  qualities  increase  and  they  produce  arid 
conditions  unless  the  process  is  repeated  by  passage  over  a  still 
higher  range.  This  process  is  well  illustrated  on  our  own  Pacific 
Coast,  where  the  moist  winds  from  the  great  ocean  are  inter- 
cepted by  the  Coast  Range,  and  a  large  part  of  their  moisture 
thereby  precipitated.  They  pass  over  the  Central  Valley 
which  is  thus  left  with  less  than  half  the  quantity  of  rainfall 
that  falls  on  the  Coast  Range.  Further  inland  the  winds  ascend 
the  high  Sierras  and  leave  on  their  summits  about  as  much 
moisture  as  precipitated  on  the  Coast  Range.  Thus  depleted 
the  winds  again  descend  to  the  plains  of  the  Interior,  as  an 


CAUSES  OF  RAINFALL 


29 


O         in          o         O         O          o 

—        —         CN        m        m         m 

o      o 


30 


WATER  SUPPLY 


.2 


CAUSES  OF  RAINFALL 


31 


m         o         "i        O 


32 


WATER  SUPPLY 


arid  atmosphere,  and  the  region  is  much  drier  than  similar 
altitudes  west  of  the  mountains. 

Whatever  the  direction  of  the  winds  the  general  law  of  con- 
densation, due  to  dynamic  cooling,  usually  causes  an  increase 
of  precipitation  with  increase  of  altitude  provided  all  other 
conditions  are  similar.  The  following  table  from  Prof.  D.  W. 
Mead  illustrates  this  law  as  manifested  in  the  Vogesen  Moun- 
tains and  also  shows  the  erratic  variations: 

TABLE  VI.— RAINFALL  IN  THE  VOGESEN  MOUNTAINS 


Station 

Altitude, 
Feet 

Rainfall, 
Inches 

Increase  per 

100   ft. 

Altitudes 

Seunheirn 

QOO 

32    28 

Thann    .                      

IIOO 

^8    IQ 

3  inches 

Weller  

I26o 

^    QO 

ii     " 

St.  Amarin  

I32O 

CTQ     06 

5  2  " 

\Vesserling 

I4.OO 

64  18 

6     " 

Odern  

ISIO 

7C    08 

10       " 

Wildenstein 

1870 

QO    21 

6     " 

' 

Mean 

6.9  inches 

This  rule,  however,  must  be  accepted  with  great  caution, 
as  there  are  numerous  exceptions  hard  to  explain,  besides  the 
manifold  differences  traceable  to  topographic  conditions. 

2.  Types  of  Rainfall. — On  the  Pacific  Coast  of  North  America 
the  precipitation  is  greatest  in  winter  and  least  in  summer, 
there  being  little  or  no  rain  from  May  to  September.  This  rule 
is  reversed  on  the  Great  Plains,  where  June  is  the  month  of 
greatest  rainfall.  A  modification  of  the  latter  type  prevails  in 
Arizona  and  New  Mexico,  where  the  greatest  rainfall  is  in  July 
and  August. 

Pacific  Type. — On  the  Pacific  Slope  there  is  a  distinct 
division  into  the  wet  and  dry  seasons,  the  wet  season  being  the 
winter  and  the  dry  the  summer.  In  the  northern  part  of  this 
belt,  on  the  coast  of  Washington,  Oregon  and  Northern  Cali- 
fornia, the  wet  season  is  long  and  the  precipitation  heavy, 
averaging  70  inches  or  more  per  annum,  and  the  dry  season 


TYPES  OF  RAINFALL 


33 


though  shorter,  is  nearly  or  quite  rainless.  Passing  southward 
the  precipitation  becomes  gradually  less,  the  rainy  season  shorter 
and  the  dry  season  longer,  until  at  the  Southern  boundary  of 


SIERRA    NEVADA 


61.18  in 


33.06  in 


PACIFIC 
OCEAN 


SACRAMENTO    VALLEY 


22  77  in  "      23<81  in 

.18 .41  in.  ,10.78  in.  .10.60  in  I 

I  K* 

ISan  FrancieccJF'irficld  |FolRonif%^ 

| Jara»cm  Z.//.|j50'  JK'        Sacramento  |  ?1>    jgoj^X 


Cisco. 


47.71  in. 


0  Sea  Level  25  miles    50 


100 


125 


150 


175; 


:I200 


225 


250 


FIG.  4. — Diagram  Showing  Effect  of  Topography  on  Rainfall  in  California  and 
Nevada.     After  Hamlin. 


FIG.  5. — Discharge  of  San  Joaquin  River  at  Herndon,  California,  1900. 

California  the  annual  precipitation  averages  less  than  10  inches, 
and  the  climate  is  distinctly  arid,  while  still  retaining  the  type 
form  of  long  dry  summers,  and  short  and  relatively  wet  winters. 


34 


WATER  SUPPLY 


Jan.          Feb.        Mar.         Apr.        May        June         July         Aug.        Sept.        Oct.         Nov.        Dec. 
10  20        10  20       10  20        10  20       10  20   I    10  20    I    10  20        10  20       10  20        10  20       10  20        10  20 


FIG.  6. — Discharge  of  Neosho  River  near  lola,  Kansas,  1900. 


Sec.-ft 

16,000 


FIG.  7. — Discharge  of  Boise  River  at  Boise,  Idaho,  1899. 


TYPES  OF  RAINFALL 


35 


Rocky  Mountain  Type. — A  contrasted  type  of  precipitation 
is  less  distinctly  marked,  but  prevails  with  some  variations 
over  most  of  the  arid  region  east  of  the  Cascade  and  Sierra 
Nevada  Mountain  Ranges.  Those  mountains  intercept  the 


FIG.  8.— Discharge  of  Salt  River  at  McDowell,  Arizona,  1899. 


20,000 


FIG.  9. — Discharge  of  Green  River  at  Green  River,  Wyoming,  1899. 

waterladen  winds  from  the  Pacific  Ocean,  and  rob  them  of 
most  of  their  moisture  during  the  winter  when  the  temperature 
is  low  enough  to  condense  the  vapors,  but  in  late  summer, 
those  winds  pass  over  the  heated  valleys  and  mountain  ranges 
and  carry  their  moisture  further  eastward,  where  the  meteoric 


36 


WATER  SUPPLY 


STREAM    FLOW  37 

fluctuations  cause  many  local  showers  and  thunder  storms, 
and  produce  a  pseudo-rainy  season  in  the  Rocky  Mountain 
Region  in  the  months  of  May  and  June,  while  the  winters  are 
drier  than  those  of  the  Sierra  Nevada  Range.  The  precipitation 
in  winter  usually  occurs  in  the  form  of  snow  except  in  the  plains 
and  valleys  of  the  south  and  near  the  Pacific  Coast,  where 
winter  rains  occur.  The  diagram,  Fig.  10,  after  Prof.  A.  J. 
Henry,  shows  several  types  of  western  rainfall,  contrasted  with 
various  eastern  types. 

In  general  the  heaviest  precipitation  is  in  the  mountains, 
which  in  winter  is  mainly  in  the  form  of  snow.  Notable  excep- 
tions occur,  however,  and  give  rise  to  contrasting  types  of 
stream  flow. 

3.  Stream  Flow. — Where  the  streams  are  mainly  fed  by 
snow,  they  have  a  comparatively  regular  habit.  The  first  warm 
days  of  spring  melt  the  snow  on  the  plains,  and  the  advancing 
season  melts  first  the  snow  in  the  foothills  aiid  on  sunny  moun- 
tain slopes,  and  as  summer  heat  increases  the  melting  increases 
in  rapidity  and  extends  to  higher  altitudes  and  to  more  shady 
slopes.  Thus  the  streams  begin  to  rise  in  early  spring  about 
the  time  of  seeding  in  the  lower  valleys,  and  continue  to  rise  as 
heat  increases,  culminating  usually  in  June  on  most  American 
streams,  declining  as  the  reserve  of  snow  diminishes,  and  reach- 
ing extreme  low  water  in  autumn  or  winter. 

This  process  has  temporary  variations  due  to  occasional 
showers  of  rain,  and  to  variations  of  temperature  affecting  the 
melting  of  snow,  which  is  accelerated  by  bright  warm  weather, 
and  checked  by  cloudy  days.  There  is  also  a  wide  variation 
in  the  snowfall  from  year  to  year,  profoundly  affecting  the  water 
supply.  A  year  of  scanty  snowfall  not  only  furnishes  a  scanty 
supply  of  water,  but  the  shortage  is  likely  to  be  concentrated 
at  the  latter  end  of  the  flood  season.  That  is,  a  scanty  snow- 
fall may  furnish  nearly  as  much  water  early  in  the  season  as  a 
year  of  abundance,  but  the  small  quantity  of  snow  is  sooner 
exhausted,  and  the  low-water  stage  arrives  earlier  in  the  season. 

Where  snowfall  plays  a  small  part  or  no  part  at  all  in  the 
flow  of  streams,  which  are  mainly  supplied  by  rains  as  some  of 


38  WATER  S&PPLY 

the  small  streams  of  the  south  and  southwest,  the  regimen 
of  the  streams  is  far  less  regular  than  that  of  those  dependent 
on  melting  snow.  Such  streams  constitute  a  second  type 
having  a  wide  variety  of  characteristics  and  far  less  susceptible 
of  approximate  prediction.  The  runoff  fluctuates  more,  and  is 
characterized  by  high  and  low  periods  succeeding  one  another 
in  quick  succession.  For  these  reasons,  a  much  larger  storage 
capacity  in  proportion  to  the  total  normal  water  supply  is 
required  on  such  streams  than  on  streams  of  the  first  type. 

Streams  of  the  first  class,  which  depend  upon  melting  snows 
for  their  main  supply,  vary  in  habit,  but  to  a  less  degree  than 
others.  In  general,  since  the  flood  season  occurs  entirely 
in  the  season  of  irrigation,  it  is  very  favorable  to  agricultural 
use,  and  a  large  proportion  can  be  thus  utilized  without  artificial 
regulation.  Examination  of  a  large  number  of  instances  shows 
the  availability  of  from  40  to  60  per  cent  of  the  total  supply 
in  normal  years  without  storage,  and  that  the  full  supply  can 
be  utilized  by  a  capacity  for  storage  of  about  40  to  60  per  cent 
of  the  total  volume.  This  storage  would  be  supplied  from  the 
winter  flow,  and  from  the  excess  supply  during  the  flood  season, 
usually  May  and  June. 

In  planning  the  full  utilization  of  a  water  supply,  the  close 
study  of  stream  flow  records  necessary  will  show  that  there  is  a 
large  variation  in  the  total  supply  from  year  to  year,  in  the  low- 
water  discharge,  and  also  in  the  maximum  flood  wave  that 
must  be  reckoned  with.  Moreover,  these  quantities  bear  only 
a  very  casual  and  uncertain  relation  to  each  other.  For  these 
reasons,  it  is  important  that  as  long  a  record  of  stream  flow  as 
possible  be  secured  before  final  determination  is  made  of  the 
possibilities  of  irrigation. 

It  will  generally  be  found  that  the  extreme  low-water  periods 
and  the  extreme  flood  waves  occur  only  at  long  intervals,  and 
it  is  usually  unwise  to  limit  development  to  the  extent  of  fur- 
nishing a  full  normal  supply  to  the  lands  served  in  the  rare 
years  of  extreme  low  water,  but  rather  to  provide  a  full  supply 
during  most  years,  and  in  the  exceptional  years  of  low  water, 
occurring  only  at  long  intervals,  be  content  with  60  or  70  per 


STREAM    FLOW  39 

cent  of  a  full  supply  for  a  brief  period.  By  more  careful  use 
and  better  cultivation  results  can  be  obtained  which  will 
approximate  the  normal,  while  the  total  development  from  the 
stream  will  be  much  greater  than  if  such  limits  were  not 
allowed. 

Where  an  enterprise  depends  largely  on  a  stored  water  supply, 
a  threatened  shortage  is  foreshadowed  by  a  shortage  in  the 
reservoir,  and  this,  in  conjunction  with  other  available  indi- 
cations, serves  as  a  warning  of  impending  scarcity,  and  farm 
operations  can  be  modified  accordingly. 

For  this  reason  it  is  admissible  to  tolerate  a  somewhat  greater 
shortage  in  low  years  under  a  stored  supply  than  if  no  storage 
is  connected  with  the  enterprise.  For  the  same  reason,  if  the 
conditions  are  such  that  the  storage  to  be  reasonably  expected 
comes  before  the  beginning  of  the  irrigation  season  in  which 
it  is  to  be  used,  a  somewhat  greater  shortage  can  be  tolerated 
than  if  dependence  is  placed  upon  the  surplus  of  May  and  June, 
which  cannot  be  certainly  known  before  the  various  farm 
enterprises  for  the  summer  are  well  under  way.  But  even  in 
this  case  there  will  be  30  to  60  days  notice  of  a  shortage,  which  is 
sufficient  to  avoid  much  wasted  labor,  and  a  few  fields  left 
fallow  on  such  occasions  are  not  a  serious  loss. 

In  most  irrigation  enterprises  the  quantity,  dependability, 
and  manner  of  occurrence  of  the  water  supply  is  of  first 
importance.  This  is  sometimes  obtained  from  wells  either  by 
pumping  or  by  artesian  flow,  which  are  treated  elsewhere.  The 
great  majority  of  irrigation  systems  obtain  their  supply  from 
natural  streams,  supplemented  in  some  cases  by  reservoirs. 

The  stream  or  streams  to  be  used  should  be  carefully  meas- 
ured at  each  point  of  diversion  and  at  each  proposed  reservoir 
site. 

Measurements  of  many  streams  of  the  West  have  been  made 
and  published  by  the  U.  S.  Geological  Survey,  and  by  some  of 
the  State  Engineers,  but  often  these  are  lacking  or  must  be 
supplemented  by  stations  located  with  special  reference  to  the 
plans  of  storage  and  diversion  under  study. 

These  measurements  to  be  a  safe  guide  must  extend  over 


40  WATER  SUPPLY 

several  years,  the  more  the  better,  and  allowance  must  be  made 
for  somewhat  greater  extremes  than  those  shown  by  the  records, 
as  it  is  highly  improbable  that  any  existing  records  show  the 
greatest  extremes  that  ever  have  occurred  or  ever  can  occur. 
The  shorter  the  record  the  greater  allowance  must  be  made  for 
this  purpose. 

The  misleading  nature  of  a  short  record  is  shown  by  the 
experience  with  the  Conconully  reservoir  in  Northern  Wash- 
ington, where  a  record  of  five  years  indicated  a  minimum  annual 
supply  of  29,000  acre-feet,  which  was  followed  by  seven  years 
in  which  the  maximum  was  24,700  and  in  which  there  were  two 
years  in  succession  of  19,220  and  15,860  acre-feet  respectively. 

4.  Laws  of  Runoff. — Where  it  is  necessary  to  study  the 
water  supply  of  a  given  stream  in  the  absence  of  actual  meas- 
urements or  with  a  very  short  record,  recourse  is  sometimes 
had  to  formulae  for  computing  runoff  from  data  regarding  rain- 
fall, evaporation,  etc.,  which  have  been  published  from  time  to 
time.  Great  caution  should  be  exercised  in  employing  any  such 
formulae,  as  the  working  data  for  this  use  is  generally  inaccurate, 
and  it  is  impossible  to  allow  properly  for  the  variations  from  the 
complicated  conditions  upon  which  such  formulae  are  based. 
It  is  necessary  to  especially  emphasize  this  caution,  as  the  formulae 
or  rules  referred  to  are  sometimes  promulgated  with  a  confidence 
that  has  no  adequate  foundation. 

The  runoff  depends  not  only  upon  the  rainfall  and  the  drain- 
age area,  but  also  upon  a  multitude  of  other  conditions  many  of 
which  are  variable,  and  none  of  which  can  be  accurately  deter- 
mined within  reasonable  time  and  cost.  The  chief  elements 
affecting  the  runoff  are  the  following: 

a.  Drainage  area  tributary  to  the  stream  above  the  point 
of  diversion.     This  can  be  determined  with  practical  exactness 
wherever  the  topographic  divide  is  definite. 

b.  The  Rainfall. — This  varies  widely  in  different  years,  and 
in  corresponding  months  of  different  years,   and   in   different 
parts  of  the  basin  in  such  an  erratic  manner  that  it  can  be  only 
roughly   approximated   in   a   large  basin  by   ordinary   feasible 
methods.     It  is  seldom  that  in  a  new  country  a  record  suffi- 


LAWS  OF  RUNOFF  41 

ciently  detailed  and  reliable  for  use  in  a  computation  of  runoff 
can  be  had. 

c.  The  Character  of  Rainfall. — A  slow  drizzling  rain  is  more 
apt  to  be  absorbed  and  later  to  evaporate  than  a  driving  storm 
which  runs  off  quickly  before  absorption.     This  factor  varies 
with  every  storm,  without  law,  and  it  is  impossible  to  define 
the    different   varieties.     The    absorption    and    residual    runoff 
also  varies  with  different  conditions  of  moisture  in-  the  soil. 
When  rain  falls  on  a  dry  baked  surface  it  is  not  readily  absorbed, 
and  largely  runs  off.     The  same  storm  falling  on  the  same  sur- 
face, moderately  moist,  is  more  easily  absorbed  and  the  runoff 
is  less.     If  the  soil  becomes  saturated,  however,  the  absorption 
ceases,  and  the  rain  runs  off. 

d.  Evaporation. — This  differs  widely  from  day  to  day  and 
from  year  to  year  with  weather  conditions,  and  especially  with 
presence  or  absence  of  moisture  to  evaporate,  and  the  varying 
relation  of  that  moisture  to  the  atmosphere. 

e.  Topography. — Steep   slopes  increase  runoff,   while  gentle 
slopes  encourage  absorption  and  evaporation. 

/.  Soil. — Bare  rock  or  clay  or  a  covering  of  thin  soil  over 
rock  or  clay  is  favorable  to  heavy  runoff,  while  a  deep  sandy  soil 
favors  absorption  and  subsequent  evaporation.  A  given  basin 
may  present  a  great  variety  of  soil  conditions. 

g.  Geologic  structure  affects  total  runoff  by  sometimes 
carrying  absorbed  water  under  ground  to  adjacent  drainage 
basins.  This  influence  is  sometimes  very  important. 

h.  Vegetation. — Other  things  being  equal  vegetation  retards 
runoff  and  subsequent  evaporation.  It  also  transpires  a  large 
amount  of  water  through  its  leaves,  and  this  varies  widely 
with  the  character  and  density  of  the  vegetation,  and  with  the 
weather. 

The  impracticability  of  expressing  accurate  mathematical 
relations  for  so  many  and  such  erratic  and  indeterminate  fac- 
tors is  obvious;  and  the  attempt  to  apply  such  relations  to  a 
different  basin  with  different  conditions  borders  on  the  absurd. 

A  knowledge  of  the  area  of  the  drainage  basin  from  which 
the  water  supply  is  to  be  drawn,  and  of  the  rainfall  at  various 


42 


WATER  SUPPLY 


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SUBSURFACE  WATER  SOURCES  45 

points  in  the  basin  extending  over  many  years  may,  if  intel- 
ligently 'studied,  and  interpreted  by  some  actual  measurements 
of  the  stream,  sheds  some  light  on  the  probable  runoff,  but  can- 
not take  the  place  of  actual  records  of  stream  flow  extending 
over  a  series  of  years. 

A  long  record  of  stream  flow  of  undoubted  accuracy  on  a 
stream  draining  a  basin  adjoining  the  one  in  question,  and 
similar  in  area,  altitude  and  topography,  may  be  available 
and  of  great  value  as  indicating  probabilities,  but  even  this 
should  be  used  with  caution,  and  can  by  no  means  take  the 
place  of  actual  measurements  of  the  stream  in  question. 

Great  caution  should  also  be  exercised  in  considering  the 
reports  of  old  inhabitants  regarding  the  annual  occurrence  of 
great  flood  discharges,  as  these  are  likely  to  be  exaggerated 
both  in  magnitude  and  frequency.  Such  floods  make  deep 
impressions  on  the  average  mind,  while  the  years  that  glide  by 
without  them  attract  less  attention,  and  are  easily  forgotten. 

5.  Subsurface  Water  Sources. — A  part  of  the  water  which 
falls  on  the  high  regions  soaks  into  the  soil  and  entering  the  pores 
and  seams  of  the  rocks  passes  slowly  along  under  ground  to  the 
lower  regions,  where  some  of  it  reappears  as  springs  and  some  is 
recovered  by  means  of  wells. 

Where  the  water-bearing  stratum  is  overlain  by  tight  material 
of  great  thickness,  preventing  the  escape  of  the  water  to  the 
surface,  the  pressure  of  the  water  from  the  hills  upon  that  in  the 
lower  parts  of  the  stratum  may  become  considerable,  and  by 
piercing  the  overlying  impervious  strata  by  drilling  machinery 
an  outlet  is  furnished  for  the  confined  water  and  under  the 
influence  of  the  accumulated  pressure  it  rises  to  the  surface, 
forming  an  artesian  well,  which  sometimes  discharges  its  water 
with  great  force,  depending  upon  the  pressure..  The  great 
majority  of  wells,  however,  do  not  flow  at  the  surface,  but  to 
be  used  must  be  raised  by  pumping. 

Irrigation  by  means  of  wells  is  well  adapted  to  individual 
effort,  where  conditions  are  favorable,  as  the  construction  of  a 
well  is  often  within  the  means  of  an  individual,  and  the  area  it 
will  irrigate  no  greater  than  he  can  control.  The  aggregate 


46  WATER  SUPPLY 

area  thus  irrigated  is  very  large  in  India,  and  has  possibilities 
of  great  development  in  this  country,  although  now  relatively 
small  as  compared  with  the  acreage  irrigated  from  streams  and 
reservoirs. 

The  water  which  enters  the  earth  by  percolation  either 
from  rain  or  from  canals,  reservoirs,  or  irrigation  finds  its  way 
through  the  soil  to  some  lower  level  where  favorable  geologic 
structure  enables  it  to  again  reach  the  surface,  or  ultimately 
reaches  a  level  which  is  comparatively  saturated.  The  surface 
of  this  zone  is  called  the  water  table,  and  varies  greatly  in  depth 
below  the  ground  surface  in  different  localities.  Its  total 
amount  is  enormous. 

a.  Rate  of  Percolation.  —  This  ground  water  is  exceedingly 
slow  of  motion,  both  in  porous  sands  and  in  the  hardest  rocks. 
It  is  known  also  that  this  ground  or  seepage  water  flows  more 
freely  at  high  than  at  low  temperatures.  At  a  mean  depth  of 
6  feet  below  the  surface  perhaps  one-third  more  water  will 
flow  in  sand  in  the  warmest  than  in  the  coldest  part  of  the  year. 
Among  the  most  important  conclusions  on  this  subject  are  those 
of  Mr.  Allen  Hazen,  which  for  closely  packed  sand  saturated 
with  water  are  expressed  in  the  formula 


60 

where  v  is  the  velocity  of  the  water  in  meters  daily  in  a  solid 
column  of  the  same  area  as  that  of  the  sand,  or  ap- 
proximately in  million  gallons  per  acre  daily; 
c  is  a  constant  factor  which  present  experiments  indicate 

to  be  approximately  1000; 

d  is  the  effective  size  of  sand  grain  in  millimeters; 
h  is  the  loss  of  head; 

/  is  the  thickness  of  sand  through  which  the  water  passes; 
/  is  the  temperature  (Fahr.). 

The  formula  can  be  used  only  for  sands  with  coefficients 
below  five  and  effective  sizes  from  o.i  to  3.0  mm.,  and  with  the 
coarser  materials  only  for  moderately  low  rates. 

Mr.  Hazen  publishes  a  table  in  his  book  showing  the  rela- 


SUBSURFACE   WATER  SOURCES 


47 


tive  quantities  of  water  at  different  temperatures  which  passed 
through  experimental  filters.  Taking  as  unity  the  quantity 
passing  at  50°  F.,  0.70  passed  at  32°  and  1.35  at  71°;  or  for  every 
three  degrees  increase  in  temperature  the  quantity  of  water 
passing  increased  by  5  per  cent.  In  the  above  the  effective 
size  is  the  size  of  grain  such  that  10  per  cent  by  weight  of  the 
particles  are  smaller  than  this.  The  uniformity  coefficient 
is  the  ratio  of  the  size  of  grain  which  has  60  per  cent  of  the  sample 
finer  than  itself  to  the  size  of  which  has  10  per  cent  finer  than 
itself. 

An  idea  of  the  slowness  of  flow  of  ground  water  may  be  had 
from  the  studies  of  Mr.  N.  H.  Darton,  who  places  the  rate  of 
motion  in  the  sands  of  the  Dakota  formation  at  a  mile  or  two 
a  year.  A  French  engineer  gives  the  same  rate,  or  an  eighth 
of  an  inch  a  minute.  In  Arizona  a  rate  of  one-fourth  of  an  inch 
a  minute,  and  in  Kansas  three-eighths  inch  a  minute,  have  been 
estimated.  At  Agua  Fria,  Arizona,  the  measured  rate  of  flow 
of  ground  water  in  creek  gravels  having  28  per  cent  voids  was 
4  feet  a  day. 

A  thin  film  of  water  is  held  on  each  particle  with  extreme 
tenacity  by  a  force  called,  "  surface  tension,"  and  where  the 
particles  are  fine  the  force  of  capillarity  is  also  strong.  In 
addition  to  this,  the  spaces  between  the  particles  a^e  so  narrow 
and  tortuous  that  water  cannot  move  through  them  except 
with  great  friction  and  extreme  slowness.  Experiments  with 
the  "  permeable  "  materials  of  the  North  Dike  at  Wachusetts 
Reservoir  gave  the  following  rates  of  percolation  through  a 
cross  section  of  1000  square  feet,  with  a  water  slope  of  10  per 
cent: 

TABLE   VIII.— PERMEABILITY  OF  SOILS 


Material 

Gallons 

Ratios 

I.    Soil     .            

51 

I 

2.  Very  fine  sand  
3    Fine  sand 

720 
9,OOO 

14 
176 

4    Medium  sand      

4OO,OOO 

784 

<    Coarse  sand                           

2,2OO,OOO 

4,353 

48 


WATER  SUPPLY 


The  experiments  of  Slichter  on  various  soils,  upon  the  veloc- 
ity of  water  at  a  temperature  of  50  degrees,  flowing  upon  a 
gradient  of  100  feet  per  mile,  gave  results  shown  in  the  following 
table,  compiled  by  Fortier: 


TABLE  IX.— VELOCITY  OF  PERCOLATION 


Kind  of  Soil 

Diam.  Grains 
m.m. 

VELOCITY 

Ft.  per  Day 

Mi.  per  Yr. 

Silt                     

O.OI 

0.04 
0.05 
0.07 

O.  IO 

0-15 
0.25 

o-35 
0.50 
0.65 
0.80 

I  .00 

3.00 
5.00 

0.004 
0.059 
0.092 
O.lSl 
0.369 
0.832 

2.305 
4.520 
9.224 

15-57 
23.62 
36.90 
332.10 
1067.00 

0.0003 
0.0041 
0.0064 
0.0125 
0.0255 
0-0575 
0.1594 

0-3125 
0.6377 
1.077 
I-633 
2.551 
22.960 
63.770 

Very  fine  sand    

Fine  sand  

Medium  sand  

Coarse  sand  

Fine  gravel  

From  the  above  it  will  readily  be  seen  that  unless  a  well  can 
be  made  to  tap  an  extensive  bed  of  coarse  material,  no  large 
yield  of  water  can  be  obtained  from  it. 

7.  Artesian  Wells. — According  to  the  common  use  of  the 
term,  an  artesian  well  is  one  from  which  water  flows  at  or  above 
the  surface  of  the  ground.  A  broader  meaning  is  any  well 
in  which  the  water  rises  considerably  above  the  stratum  to 
which  it  was  confined  before  being  relieved  by  the  construction 
of  the  well.  The  former  is  the  more  generally  accepted  as  well 
as  the  more  practical  definition. 

In  order  that  water  may  rise  in  a  well  to  the  ground  surface, 
it  must  be  under  pressure,  and  so  confined  between  relatively 
impervious  deposits,  that  it  can  more  easily  escape  through 
the  well  than  elsewhere. 


ARTESIAN  WELLS  49 

if  a  stratum  of  sand,  sandstone,  gravel,  or  other  porous 
material  is  confined  between  relatively  impervious  strata  of 
rock  or  clay,  and  is  so  inclined  that  one  part  of  the  open  material 
is  exposed  to  rain,  and  another  part  is  depressed  in  the  form 
of  a  basin,  the  water  entering  at  the  upper  edge  will  percolate 
down  the  slope  of  stratification  and  accumulate  in  the  basin, 
and  place  the  water  in  the  lower  levels  under  such  pressure  as 
corresponds  to  the  hydrostatic  head  of  the  water  above  it.  If 
now  the  overlying  clay  be  perforated  by  a  boring,  the  water 
will  rise  in  the  bored  well  to  the  same  height  as  the  source  from 
which  the  pressure  is  derived,  and  if  this  is  sufficient  to  force 
the  water  to  the  surface,  we  have  a  flowing  well. 

The  accompanying  diagram,  Fig.  u,  illustrates  the  geo- 
logical conditions  of  an  artesian  basin. 


FIG.  ii. — Ideal  Section  Illustrating  Condition  of  Artesian  Wells. 

If  the  layer  of  sand  be  penetrated  by  a  well  drilled  at  D, 
the  water  will  rise  to  a  height  regulated  by  the  pressure  of  the 
water  in  the  sand  above  the  locality  where  the  well  reaches  it. 

The  source  of  the  water  that  rises  in  artesian  wells  is  mainly 
the  precipitation  on  the  edges  of  the  pervious  beds  where  they 
come  to  the  surface.  In  some  instances  the  porous  beds  are 
charged  in  this  way  at  their  outcrops,  hundreds  of  miles  from 
where  the  water  is  liberated  by  drilling  wells. 

The  height  to  which  water  rises  in  an  artesian  well,  or,  the 
height  to  which  it  would  rise  in  a  tube  open  at  the  top,  if  prop- 
erly attached  to  the  well,  is  termed  the  "  artesian  head." 
This  is  illustrated  in  the  waterworks  of  towns,  where  the  water 
rises  in  the  distributing  pipes  to  the  same  level  as  the  surface 
of  the  water  in  the  reservoir  from  which  it  is  drawn. 

Cases  also  occur  of  what  are  termed  incomplete  artesian 
basins,  where  an  inclined  bed  of  open  material  as  sand  or 
gravel  thins  out  at  its  lower  edge,  and  the  impervious  strata 


50  WATER  SUPPLY 

above  and  below  approach  each  other.     This  is  illustrated  in 
Fig.  12. 

It  will  be  noted  that  stratification  and  porosity  are  two  neces- 
sary conditions  and  therefore  massive,  unstratified,  crystalline 
rocks  such  as  granite,  schists  quartzites  and  diorites,  which  are 
not  porous,  and  are  never  underlain  with  porous  stratified  rocks, 
do  not  present  favorable  conditions  for  artesian  wells.  Where 
such  rocks  are  exposed  or  occur  near  the  surface  of  the  ground, 
the  prospects  for  artesian  water  are  poor.  The  original  bedding 
of  such  rocks  has  been  generally  obliterated  by  the  changes 
they  have  undergone,  and  there  is  no  succession  of  pervious  and 
impervious  layers. 


FIG.    12. — Ideal  Section  Illustrating  Thinning  Out  of  Water-bearing   Stratum. 

The  condition  of  a  flowing  well  depends  on  whether  the 
pressure  is  sufficiently  great  to  force  the  water  above  the  sur- 
face. Frequently  the  water  will  reach  within  but  a  few  feet 
of  the  surface,  when  an  ordinary  well  or  shaft  can  be  excavated 
and  the  water  pumped  to  the  desired  height.  In  many  other 
cases  the  pressure  is  such  that  the  water  spouts  forth  from  the 
well  under  pressure  to  considerable  heights.  In  the  San  Gabriel 
and  San  Bernardino  valleys  in  Southern  California  and  many 
other  regions,  it  has  been  found  that  after  a  number  of  wells 
have  been  sunk  each  additional  well  affects  its  neighbors  by 
diminishing  their  discharge.  There  thus  comes  a  point  in  the 
sinking  of  wells  when  the  number  which  can  be  utilized  in  any 
given  area  or  basin  is  limited. 

a.  Examples  of  Artesian  Wells. — Some  great  wells  have 
been  sunk  in  different  parts  of  the  world.  The  celebrated  Grin- 
nell  well  in  Paris  commenced  with  a  20-inch  bore  and  is  gradually 
reduced  to  an  8-inch  bore  at  the  bottom;  its  depth  is  1806  feet, 
and  its  yield  has  been  as  great  as  1.5  second  feet.  A  well  has 
been  bored  in  the  neighborhood  of  Wheeling,  West  Virginia, 


ARTESIAN   WELLS  51 

to  the  great  depth  of  4500  feet,  but  is  dry.  At  Sperenberg, 
near  Berlin,  is  a  well  4170  feet  deep,  and  at  Schladabach,  near 
Leipsic,  is  a  well  5740  feet  in  depth.  In  St.  Louis  is  a  well 
which  reaches  a  depth  of  3850  feet,  about  3000  feet  below  the  sea- 
level.  In  San  Bernardino  and  San  Gabriel  valley  in  Southern 
California  and  in  the  upper  San  Joaquin  valley  in  the  neighbor- 
hood of  Bakersfield  are  some  extensive  artesian  areas,  and 
great  artesian  basins  are  found  in  the  neighborhood  of  Waco, 
Texas,  Denver,  Colorado,  and  the  James  River  valley  and  the 
neighborhood  of  Huron  in  the  Dakotas. 

b.  Capacity  of  Artesian   Wells. — The   capacities  of   flowing 
wells  are  relatively  small  as  compared  with  the  volumes  of 
water    required    in    irrigation.      Of    the    thousands    of    wells 
reported  from  the  arid  region  comparatively  few  are  of  sufficient 
capacity  for  use  in  irrigation.     The  great  majority  range  from  100 
to  200  feet  in  depth,  from  2  to  4  inches  in  internal  diameter,  and 
discharge  rarely  as  much  as  o.i  of  a  second-foot;    though  this 
volume,  if  stored  in  a  suitably  located  reservoir,  should  irrigate 
a  small   farm.     On   the   other   hand    there    are,    especially    in 
South   Dakota   and   Southern    California,  some  very  large  flow- 
ing wells.     In  the  former  State  there  are  reported  to  be  at  least 
twenty-five  wells  with  discharges  ranging  from  i  to  6  second-feet, 
and  in  Southern  California  about  thirty  wells  of  similar  capacities. 
The  largest  well  in  South  Dakota  delivers  continuously  about 
6.68  second-feet. 

c.  Storage  of  Artesian  Water. — An  artesian  well  for  irrigation 
should  if  possible  be  on  the  highest  point  of  the  land  to  be 
irrigated,  and  in  such  a  position  that  it  may  be  outside  of  and 
tributary  to  the  reservoir  in  which  the  water  is  to  be  stored. 
Since    artesian    wells    flow    continuously    during    twenty-four 
hours  of  the  day  and  three  hundred  and  sixty-five  days  in  the 
year,  it  is  desirable  to  store  as  much  of  the  water  which  flows 
during  the   non-irrigating  period  as  possible,  in  order  that  the 
greatest  duty  may  be  gotten  from  the  well.     The  volume  flowing 
continuously  from  almost  any  well  is  usually  too  small  to  enable 
it  to  flow  over  the  land  in  sufficient  volume  for  the  purposes  of 
irrigation,  so  that  a  necessary  adjunct  to  nearly  every  well  is  a 


52  WATER  SUPPLY 

storage  reservoir  of  greater  or  less  dimensions.  In  the  case,  how- 
ever, of  a  well  which  discharges  about  i  second-foot,  or  enough 
to  irrigate  100  acres  from  unstored  flow,  such  a  well  may  be 
made  capable  of  irrigating  several  times  this  area  if  the  water 
flowing  at  other  times  than  the  irrigating  periods  can  be  stored. 
Small  reservoirs,  sufficiently  large  to  retain  only  enough  water 
to  produce  the  requisite  head  for  flowing  over,  may  be  built  as  are 
watering-tanks  on  railways,  or  they  may  be  cheaply  excavated 
in  the  highest  ground  on  the  farm  and  properly  lined.  Larger 
ones  may  be  constructed  by  making  use  of  the  natural  configura- 
tion of  the  country  and  building  a  dam  across  a  hollow  or 
ravine. 

d.  Size  of  Well. — The  yield  of  a  well  does  not  depend  entirely 
upon  its  size.  A  6-inch  well  will  not  necessarily  discharge 
more  water  than  a  3 -inch  well — perhaps  not  as  much.  The 
amount  of  flow  depends  directly  upon  the  volume  of  the  water- 
bearing strata  and  the  pressure  due  to  its  initial  head  or  source. 
Providing  this  is  sufficiently  great,  then  the  discharge  of  the  well 
is  dependent  on  its  diameter.  Other  things  being  equal,  a  large 
well  will  cost  more  to  drill,  but  will  be  more  easily  and  cheaply 
cleaned  and  kept  in  operation  than  a  smaller  one,  which  is  apt  to 
clog.  Further,  during  and  after  drilling  an  accident  may  ruin  a 
small  well,  while  a  larger  one  may  be  recased  with  diminished  bore 
and  still  remain  serviceable.  For  purposes  of  irrigation  it  may 
in  general  be  said  that  a  well  less  than  4  inches  in  diameter  should 
not  be  drilled,  and  it  is  probable  that  one  with  a  bottom  bore 
greater  than  8  inches  will  not  be  economical. 

Nearly  all  wells  which  terminate  in  soft  rock,  sand,  or  gravel 
discharge  more  or  less  of  these  materials.  To  prevent  this  from 
clogging  the  well  it  is  not  uncommon  to  place  perforated  pipe  in 
the  bottom  of  the  well  through  the  water-bearing  stratum.  There 
are  many  styles  of  such  pipe,  but  in  general  it  may  be  stated  that 
pipe  with  circular  perforations  of  uniform  diameter  is  not  the 
most  serviceable,  as  it  is  apt  to  become  clogged.  Some  of  the 
patented  perforated  pipes  with  slots  having  less  aperture  on  the 
outer  than  on  the  inner  surface  are  preferable.  In  some  cases 
experience  may  show  that  it  is  not  desirable  to  insert  perforated 


ARTESIAN  WELLS  53 

pipe,  but  to  let  whatever  comes  to  the  well  be  discharged  and 
collected  in  the  storage  reservoir. 

e.  Manner  of  Having  Wells  Drilled. — There  are  many  respon- 
sible firms  who  make  a  business  of  drilling  and  boring  artesian 
wells,  and  for  those  who  are  unfamiliar  with  the  business  of 
well-sinking  it  is  better  to  contract  with  some  such  firm  to 
perform  the  work  required.  On  the  other  hand,  the  sinking  of 
a  well  is  not  a  difficult  operation  for  those  who  have  .any  idea  of 
the  process,  though  by  contracting  they  are  certain  of  having 
the  well  sunk  as  they  desire,  within  a  fixed  price,  and  are  relieved 
of  the  risk  of  accidents. 

In  the  oil  and  gas  regions  the  drilling  of  wells  to  tap  oil-  and 
gas-bearing  strata,  which  is  a  process  entirely  similar  to  that 
of  drilling  wells  for  water,  is  a  matter  of  every-day  occurrence, 
and  nearly  all  who  desire  to  sink  wells  perform  the  work  on  a 
sort  of  half-contract  system.  The  principal  apparatus  com- 
prises an  engine,  boiler,  carpenter's  rig,  and  set  of  drilling  tools, 
and  the  common  practice  is  for  the  owner  to  provide  all  except 
the  tools  and  fuel  and  let  the  drilling  of  the  well  at  so  much  a 
foot  to  a  contractor  who  furnishes  these  and  does  the  work  of 
putting  down  the  well. 

/.  Varieties  of  Drilling-machines. — Wells  may  be  drilled 
by  various  methods,  among  the  chief  of  which  are  by  cables, 
poles,  and  hydraulic  process.  Provided  the  well  is  to  be  drilled 
by  contract,  it  is  of  little  importance  what  method  is  employed, 
since  the  contractor  is  responsible  for  the  proper  completion 
of  the  work,  and  the  style  of  rig  is  a  matter  for  his  own  choice. 
In  the  Dakotas  and  some  other  of  the  plains  regions  it  has  been 
found  that  wells  drilled  with  pole  machines  have  proved  most 
satisfactory  and  performed  the  cheapest  work,  aside  from  the 
amount  of  time  taken  in  coupling  and  uncoupling  the  rods.  In 
the  oil-and  gas-bearing  regions  cable  machines  are  most  popular. 
There  are  many  patterns  of  hydraulic,  jetting,  and  rotar^y  rigs 
which  are  adopted  by  different  well-boring  firms.  The  latter 
are  dependent  upon  a  rotary  motion  given  to  a  piston-rod  working 
by  hydraulic  power  and  turning  a  tubing  with  cutting  edge.  In 
hydraulic  jetting  machines,  which  can  be  used  cheaply  only  in 


54  WATER  SUPPLY 

gravel  or  sand,  there  is  employed  a  short  drill-bit  having  a  hollow 
shank  through  which  a  jet  of  water  is  forced  from  pipe  rods, 
thus  creating  an  upward  current  which  carries  out  the  drillings. 
Some  of  these  hydraulic  and  jetting  machines  have  met  with 
remarkable  success. 

The  chief  advantage  of  pole  rigs  over  cable  rigs  is  in  the 
certainty  of  the  revolutions  given  to  the  drill,  as  the  rods  form 
a  rigid  connection  between  the  drill  and  the  machine  above, 
and  the  motion  is  uniform  in  the  direction  of  tightening  the 
screws  of  the  joints.  This  tends  to  preserve  the  connection, 
and  keep  the  drill  under  perfect  control.  Cable  rigs  are  chiefly 
preferred  because  of  the  ease  with  which  they  can  be  operated 
and  the  speed  with  which  the  tools  can  be  lowered  and  removed 
and  the  bailing  apparatus  substituted  in  their  place.  The  chief 
disadvantages  as  compared  with  the  pole  rigs  is  in  the  greater 
friction  produced  by  the  corrugated  surface  of  the  cable,  the 
uncertainty  as  to  whether  the  striking  bar  reaches  the  bottom 
of  the  drill,  the  likelihood  of  cutting  or  bending  the  cable,  and 
the  danger  of  breaking  under  the  strain  when  tools  become  fast. 
As  the  cable  is  rotated  both  to  the  right  and  left  there  is  also 
liability  of  uncoupling  the  joints  at  the  tools,  and  there  is  a  pos- 
sibility that  the  cable  may  not  produce  the  proper  rotation  in 
the  drill,  and  thus  not  bore  the  hole  truly  circular.  There  are 
now  on  the  market  a  number  of  excellent  portable  well-drilling 
rigs,  both  of  the  old  reliable  walking-beam  type  (Fig.  13),  and 
also  jetting  and  hydraulic  rotary  rigs.  These  can  frequently 
be  purchased  outright  at  prices  which  will  render  them  cheaper 
than  any  other  method  of  having  wells  drilled. 

g.  Process  of  Drilling. — The  general  process  of  drilling 
consists  in  having  a  long,  heavy  drilling-bar,  the  lower  end  of 
which  is  dressed  to  a  cutting  edge,  which  is  dropped  into  a  hole 
in  the  rock  and  by  its  weight  cuts  or  breaks  the  stone  where  it 
strikes.  At  each  blow  this  rod  is  turned  a  little,  thus  making 
the  hole  round.  The  drill  is  hung  from  the  end  of  a  cable  or 
series  of  jointed  poles  which  are  raised  and  dropped  by  machinery. 
After  the  drill  has  worked  for  a  short  time  it  is  removed,  and 
the  drillings,  or  small  pieces  of  rock  which  have  collected  in  the 


ARTESIAN  WELLS  55 

bottom  of  the  hole  and  deaden  the  blow  of  the  drill,  are  removed. 
This  is  done  by  pouring  water  in  the  hole  if  it  be  dry,  and  the 
fluid  mud  thus  formed  is  lifted  to  the  surface  by  a  long,  narrow 
bailer  with  a  valve  at  its  lower  end.  These  operations  of  drilling 
from  3  to  5  feet,  then  cleaning  out  the  mud  and  drilling  again, 
are  alternated  until  the  desired  depth  is  reached.  If  casing 
or  lining  is  to  be  introduced  and  the  hole  is  not  drilled  truly 


FIG.  13. — Portable  Artesian-well  Drilling  Rig. 

cylindrical,  it  is  reamed  out  by  a  steel  tool  of  desired  diameter, 
weighing  about  125  pounds  and  attached  in  place  of  the  drill. 

The  apparatus  which  goes  to  make  a  drilling-machine  com- 
prises an  engine  and  boiler  of  about  20  horse-power,  a  set  of 
drilling- tools,  and  cable  or  poles.  These  latter  are  generally 
spoken  of  as  the  rig.  It  is  also  necessary  to  provide  tubing  or 
casing  to  line  the  well  through  such  permeable  strata  as  might 
cause  the  loss  of  water  or  through  such  strata  as  may  provide 
water  which  is  undesirable  for  the  purposes  required.  It  is  some- 
times necessary  to  line  wells  with  tubing  throughout  their  entire 


56  WATER  SUPPLY 

length,  and  in  such  cases  it  is  usual  to  begin  with  a  large  bore,  say 
8  inches,  and  after  sinking  this  to  a  given  depth,  say  200  or  300 
feet,  to  reduce  the  diameter  of  the  tubing  by  an  inch  or  two. 

The  "  set  of  tools  "  which  compose  the  drill — for  the  latter 
is  not  a  solid  bar,  but  several  pieces — weigh  about  2500  pounds, 
and  consist  of  a  steel  "  bit  "  or  "  drill,"  of  the  size  of  the  bore 
desired,  screwed  into  the  lower  end  of  the  "  auger  stem,"  which 
latter  is  a  steel  rod  30  feet  long  and  3  inches  in  diameter.  To 
the  upper  end  of  this  are  screwed  "  jars,"  and  above  them  the 
"  sinker-bar,"  which  is  15  feet  long  and  3  inches  in  diameter, 
and  of  steel.  The  jars  by  slacking  together  in  falling  cause  the 
sinker-bar  to  act  on  and  through  them  to  the  drill  as  a  hammer. 
The  term  "  rig  "  generally  includes,  in  addition  to  the  set  of  tools, 
the  woodwork  and  necessary  iron  fittings  forming  a  derrick  to 
carry  a  sheave  at  a  sufficient  height,  perhaps  50  to  80  feet,  to 
swing  the  drilling- tools  clear  of  the  ground;  also,  both  wheels 
and  shaft  on  which  the  drill  cable  is  wound;  the  sand-reel  for 
winding  up  the  smaller  rope  used  in  cleaning  out  the  drillings; 
a  walking-beam  to  give  vertical  motion,  and  a  band- wheel  for 
transmitting  power  from  the  engine  to  the  moving  parts. 

After  the  engine  has  been  started  and  the  walking-beam  is 
made  to  rock  up  and  down  at  the  rate  of  20  to  30  strokes  a  minute, 
lifting  the  tools  with  it,  the  length  of  stroke  being  adjustable 
from  15  inches  to  3  feet,  the  rope  is  then  twisted  by  means  of  a 
stick,  first  in  one  direction  for  a  while  and  then  in  the  opposite 
direction  alternately.  This  twisting  of  the  rope  turns  the  drill, 
and  the  driller  who  handles  the  rope  knows  by  the  "  feel  "  how 
the  tools  are  working,  the  texture  of  the  rock,  and  the  occurrence 
of  an  accident.  Occasionally  the  temper  and  set-screws  are 
turned  out  a  little,  thus  lowering  the  tools.  After  the  drilling 
has  gone  on  to  a  depth  of  4  or  5  feet  the  tools  are  hoisted  clear 
of  the  floor,  the  bull-rope  swung  off  to  one  side,  and  the  bailer 
or  sand-pump  is  swung  over  the  hole  from  the  sand-reel,  and 
is  allowed  to  drop  by  its  own  weight,  and  upon  reaching  the 
bottom  is  filled  with  mud  and  sand  through  the  valve  at  its  lower 
end  and  is  then  drawn  up  and  emptied;  this  process  being 
repeated  if  necessary  to  clear  the  hole  before  drilling  is  again 


ARTESIAN  WELLS  57 

resumed.  The  rate  of  drilling  depends  partly  upon  the  character 
of  strata  encountered,  but  averages  from  15  to  50  feet  per  working 
day. 

A  method  of  deep-well  construction  employed  in  California 
and  known  as  the  stovepipe  method  is  admirably  adapted  to 
conditions  where  the  material  to  be  drilled  consists  of  coarse 
debris.  Casing  from  10  to  14  inches  in  diameter  is  put  down, 
reaching  in  one  instance  to  1300  feet  in  depth.  A  starter  is  used 
consisting  of  a  length  of  15  to  25  feet  of  No.  10  riveted  sheet  steel 
with  a  sharpened  steel  shoe.  The  remainder  of  the  casing  above 
is  of  No.  12  sheet  steel  in  lengths  of  only  2  feet,  each  following 
section  being  smaller  than  the  last  so  as  snugly  to  telescope  for 
i  foot  of  length,  thus  forming  a  double  shell  of  stovepipe  casing. 
This  is  sunk  by  the  ordinary  oil-well  type  of  machinery,  the  casing 
being  forced  down,  however,  by  hydraulic  jacks.  After  the  well 
is  sunk  a  cutting  knife  is  lowered  into  it  and  vertical  slits  are  cut 
in  the  casing  opposite  water-bearing  strata. 

The  advantages  of  these  methods  are:  absence  of  short  fragile 
screw- joints ;  flush  outer  surface  which  does  not  catch  in  clay  or 
projecting  rocks;  its  elastic  character  permits  it  to  adjust  itself 
to  obstacles  and  stresses;  its  cheapness  for  large  sizes  of  casing; 
the  short  sections  permit  the  hydraulic  jacks  to  force  it  down; 
the  ability  to  perforate  the  casing  at  any  depth  with  a  large  size 
of  perforation  inside. 

The  cost  of  such  wells  averages  about  $i  per  foot  for  casing; 
$40  for  the  starter;  and  for  the  drilling  50  cents  per  foot  for  the 
first  100  feet,  thereafter  25  cents  additional  for  each  succeeding 
50  feet. 

h.  Capacity  of  Common  Wells. — The  supplying  capacity 
of  common  wells  is  frequently  increased  considerably  by  irriga- 
tion. As  water  is  applied  to  the  soil  through  a  period  of  years 
the  subsurface-water  plane  rises,  and  it  may  be  reached  at  lesser 
depths  than  previously.  In  this  way  irrigation  water  may  be 
used  over  several  times;  by  pumping  it  from  wells  it  may  find 
its  way  by  seepage  back  to  the  streams,  from  which  it  may  be 
again  diverted.  The  capacity  of  surface  or  common  wells 
depends  on  the  degree  of  fineness  of  the  water-bearing  stratum, 


58  WATER  SUPPLY 

fine-grained  material  yielding  water  more  slowly  and  of  less 
amount  than  coarser  material.  The  yield  also  depends  on  the 
head  or  depth  below  the  surface  of  the  water-table  at  which 
the  flow  takes  place;  also  upon  the  size  and  shape  of  the  exca- 
vation and  character  of  the  well  walls  or  casing.  The  yield 
is  directly  proportional  to  the  freedom  with  which  the  water- 
bearing material  permits  the  movement  of  water,  and  also  to  the 
head  or  depth  by  which  the  water-table  is  lowered.  Of  a  series 
of  wells  across  the  Rio  Grande  valley  near  Las  Cruces,  N.  M., 
those  near  the  river,  in  fine  compact  deposits  of  the  valley  bottom, 
have  a  small  yield  compared  with  the  greater  capacity  of  wells 
some  distance  from  the  river,  under  the  mesa  foot  in  the  coarser 
mountain  debris.  If  the  well  is  shallow,  increasing  the  diameter 
increases  the  flow;  but  if  deep  and  relatively  small  in  diameter, 
as  a  pipe,  increasing  the  diameter  does  not  appreciably  increase 
the  flow. 

The  extent  to  which  common  wells  may  be  used  as  a  source 
of  supply  for  irrigation  is  not  appreciated  in  the  United  States, 
where  as  yet  irrigation  is  practiced  only  in  a  large  way  and 
irrigators  are  but  just  coming  to  a  realization  of  the  advantages 
of  intensive  cultivation,  whereby  but  a  few  acres  are  worked  by  a 
single  farmer,  but  in  the  most  thorough  manner  possible.  In  a 
few  portions  of  the  Far  West,  notably  in  Central  and  Southern 
California,  where  Italians  and  Chinamen  are  engaged  chiefly 
in  market-gardening,  wells  are  employed  to  some  extent  for  the 
supply  of  water.  In  such  cases  the  water  is  raised  by  one  of 
several  processes,  chiefly  by  windmills,  and  by  mechanical  lifts 
worked  by  horse-power,  and  similar  to  the  Persian  wheel  of 
Asia. 

It  is  to  India  that  we  must  look  in  order  to  gain  an  idea  of 
the  extent  to  which  wells  may  furnish  irrigation  water.  In  the 
Central  Provinces  of  India  1 20,000  acres  are  irrigated  from  wells. 
In  Madras  2,000,000  acres  are  irrigated  from  400,000  wells. 
In  the  Northwest  Provinces  360,000  acres  are  irrigated  from 
wells.  Some  of  these  wells  are  sunk  to  depths  as  great  as  80 
to  100  feet,  in  some  cases  through  hard  rock,  and  are  capable 
in  ordinary  seasons  of  irrigating  from  i  to  4  acres  each.  These 


TUNNELING  FOR   WATER  59 

wells  may  really  be  said  to  supplement  irrigation  from  canals 
and  reservoirs,  for  after  the  waters  of  the  latter  have  been  used 
and  have  seeped  into  the  soil  they  are  caught  by  the  well  and 
are  again  used  for  irrigation.  Thus  wells  as  an  adjunct  to 
canals  may  be  said  to  add  materially  to  the  duty  of  the  latter. 

8.  Tunneling  for  Water. — Tunnels  are  sometimes  driven  in 
sloping  or  sidehill  country  to  tap  the  subterranean  water- 
supplies.  These  are  practically  horizontal  wells,  differing  from 
ordinary  wells  chiefly  in  that  the  water  has  not  to  be  pumped 
to  bring  it  to  the  level  of  the  surface,  but  finds  its  way  by  gravity 
flow  to  the  lands  on  which  it  is  to  be  utilized.  Near  the  Khojak 
Pass  in  India  is  a  great  tunnel  of  this  kind.  This  is  run  near  the 
dry  bed  of  a  stream  into  the  gravels  for  a  distance  of  over  a  mile. 
The  slope  of  its  bed  is  3  in  1000,  its  cross-section  is  1.7X3  feet, 
and  its  discharge  about  9  second-feet.  The  Ontario  Colony  in 
Southern  California  derive  their  water-supply  from  a  tunnel  3300 
feet  in  length,  run  under  the  bed  of  San  Antonio  creek  through 
gravel  and  rock.  Its  cross-section  is  5  feet  6  inches  high, 
3  feet  6  inches  wide  at  bottom,  and  2  feet  wide  at  top.  It 
is  partly  timbered  and  partly  lined  with  concrete,  having  weep- 
holes  in  the  upper  part  of  the  tunnel.  Its  discharge  is  about 
6  second-feet.  The  supply  from  several  subtunnels  has  been 
such  as  to  average  nearly  10  second-feet  per  linear  mile  of  tunnel. 

The  Spring  Valley  Water  Company  which  supplies  San 
Francisco,  California,  has  recently  made  some  of  the  most 
extensive  developments  of  water  from  subsurface  sources  yet 
recorded.  One  bed  of  gravel  in  a  stream  valley  having  an  area 
of  1 200  acres  absorbs  practically  all  the  drainage  of  300  square 
miles.  Into  these  gravels  were  sunk  91  wells  which  yield  36 
acre-feet  of  water  per  day.  Another  similar  bed  has  been 
developed  by  drifting  over  14,000  feet  of  tunnel  5  feet  6  inches  X 
5  feet  6  inches  with  nearly  as  great  a  length  of  smaller  branch 
tunnel.  Into  this  drain  several  hundred  driven  wells  (Fig.  14) 
which  yield  over  45  acre-feet  of  water  per  iay. 

a.  Underground  Cribwork. — Submerged  cribs  were  planned 
for  the  American  Water  Company  on  Cherry  Creek  in  Colorado, 
and  have  been  used  by  the  Citizens'  Water  Company  on  the 


60 


WATER  SUPPLY 


South  Fork  of  the  Platte  River  in  Colorado.  The  former  enter- 
prise contemplated  a  submerged  open  crib  sunk  in  the  gravel 
bed  of  Cherry  Creek,  and  resting  on  blue  clay  which  is  73  feet 
below  the  surface  of  the  stream,  rising  to  a  height  of  70  feet, 
with  its  crest  3  feet  below  the  bed  of  the  stream.  This  was  not  to 
be  a  dam,  but  to  stop  the  movement  of  that  portion  of  the  sub- 
surface water  which  might  enter  the  cribwork.  It  would  consist 
of  timbers  14  inches  in  dimension  at  the  bottom,  decreased  to  8 


FIG.  14. — Subterranean  Water  Tunnel  and  Feed- wells:  California. 

inches  at  the  top,  placed  4  feet  apart  across  stream,  and  planked 
on  both  faces  with  interstices  of  3  inches  on  the  upper  face. 
The  water  caught  in  this  cribwork  was  to  be  pumped  to  the 
surface. 

The  Citizens'  Water  Company  develops  the  underground 
waters  of  the  Platte  River  by  means  of  a  series  of  gathering-gal- 
leries, consisting  of  perforated  pipe  and  open  cribwork  laid  at 
a  depth  of  from  14  to  22  feet  below  the  surface  of  the  gravel  bed 
of  the  stream.  The  cribs  (Fig.  15)  are  30  inches  square,  and 
about  a  mile  of  these  have  been  built  running  up  the  bed  of  the 


OTHER  SUBSURFACE  WATER  SOURCES 


61 


stream,  besides  about  a  mile  of  perforated  pipe  30  inches  in 
diameter.  The  average  daily  yield  obtained  by  these  galleries 
is  nearly  10  acre-feet  of  water,  which  is  led  off  through  the  pipes 
by  natural  'flow. 

9.  Other  Subsurface  Water  Sources. — Earth  waters  may  be 
gathered  for  irrigation  by  other  means  than  springs,  common 
or  artesian  wells,  or  tunnels.  In  the  dry  beds  of  streams 
in  California  submerged  dams  have  been  built  which'  reach  to 
some  impervious  stratum  and  cut  off  the  subterranean  flow,  thus 


FIG.  15. — Gathering-cribs,  Citizens'  Water  Co.,  Denver. 

bringing  water  to  the  surface.  In  portions  of  the  plains  region, 
especially  in  Kansas,  subsurface  supplies  have  been  obtained 
by  running  long  and  deep  canals  parallel  to  the  dry  beds  of 
streams  or  in  the  low  bottom  lands  and  valleys.  These  canals, 
acting  Hke  drainage  ditches,  receive  a  considerable  supply  of 
water  and  lead  it  off  to  the  lands.  It  may  be  generally  stated 
that  the  amounts  of  water  to  be  derived  by  such  means  are 
very  limited  and  do  not  approach  those  claimed  by  the  advocates 
of  so-called  "  underflow." 

10.  Character   of   Water. — Practically  all  waters   found  in 
nature   contain   some   dissolved   mineral  matter.      Spring   and 


62  WATER  SUPPLY 

well  waters  usually  contain  more  than  surface  storm  waters, 
and  those  of  the  arid  region  more  than  those  of  humid  regions 
This  follows  from  the  fact  that  the  soils  of  arid  regions  contain 
more  soluble  salts  than  those  of  more  humid  climes,  because 
the  latter  have  generally  been  more  thoroughly  leached. 

Cases  are  numerous  -where  small  streams  fed  by  mineral 
springs  carry  injurious  salts  in  such  quantity  as  to  be  unfit 
for  irrigation,  and  to  seriously  impair  the  quality  of  rivers  into 
which  they  flow.  The  amount  of  mineral  which  water  may 
carry  and  still  be  suitable  for  plant  consumption  depends  of 
course  on  the  character  of  the  salt,  and  in  general  the  salts 
of  sodium  are  most  to  be  feared,  in  the  order  of  carbonate, 
chloride  and  sulphate. 

As  a  result  of  his  investigations  in  northern  Africa,  Mr. 
Thomas  H.  Means  states  that  the  amount  of  soluble  matter  allow- 
able in  an  irrigation  water  has  been  greatly  underestimated,  and 
that  many  sources  of  water  which  have  been  condemned  can  be 
used  with  safety  and  success  with  proper  precautions.  The  Arabs 
in  the  Sahara  he  says  sometimes  grow  vegetables  with  water 
containing  as  high  as  800  parts  of  soluble  salts  to  100,000  parts 
of  water,  sometimes  50  per  cent  of  the  salts  being  sodium  chloride. 
The  Arab  gardens  consist  of  small  plots  20  feet  square,  between 
which  are  drainage  ditches  dug  to  a  depth  of  about  3  feet.  This 
ditching  at  short  intervals  insures  rapid  drainage.  Irrigation 
is  by  the  check  method  and  application  made  at  least  once  a 
week,  sometimes  oftener.  A  large  quantity  of  water  is  used  at 
each  irrigation,  thus  securing  the  continuous  movement  of  the 
water  downward,  permitting  little  opportunity  for  the  soil  water 
to  become  more  concentrated  when  the  irrigation  water  is  applied, 
and  there  is  little  accumulation  of  salt  from  the  evaporation  at 
the  surface.  What  concentration  or  evaporation  accumulation 
does  occur  is  quickly  corrected  by  the  succeeding  irrigation. 

Under  average  conditions,  however,  where  the  total  soluble 
salts  exceed  300  parts  in  100,000,  water  is  objectionable  for 
irrigating  most  crops,  and  if  carbonates  are  present  a  lower  limit 
is  imposed,  and  if  they  predominate,  a  still  lower  limit  must 
be  set. 


CHARACTER  OF  WATER  63 

Waters  which  contain  a  moderate  amount  of  salts  may  be 
entirely  suitable  for  irrigation  on  soils  having  good  drainage, 
but  if  irrigation  with  such  waters  is  long  continued  and  no 
measures  are  taken  to  prevent  the  accumulation  of  salts  in  the 
soil,  they  may  in  time  impair  its  fertility.  Deep  drainage  and 
occasional  copious  irrigation  is  the  preventive  and  the  remedy. 
These  are  treated  at  greater  length  in  Chapter  XII. 

REFERENCES  FOR  CHAPTER  V 

ALEXANDER,  W.  H.  Relation  of  Rainfall  to  Mountains.  Monthly  Weather  Re- 
view, 1901,  p.  6. 

MEAD,  DANIEL  W.     Hydrology.     Part  II.     University  of  Wisconsin. 

TALBOT,  A.  N.     Rates  of  Maximum  Rainfall.     Technograph,  1891-2. 

HOYT,  J.  C.  Comparison  between  Rainfall  and  Runoff  in  the  Northeastern 
United  States.  Trans.  Am.  Soc.  C.  E.,  Vol.  LIX,  New  York.  Discussions 
of  Above. 

KUICHLING,  EMIL.  Unusual  Flood  Discharges.  Trans.  Am.  Soc.  C.  E.,  Vol. 
LXXVII,  p.  650. 

HENSHAW,  LEWIS  and  MCCAUSLAND.  Deschutes  River  and  Its  Utilization. 
W.  S.  P.  344,  U.  S.  Geological  Survey. 

LARUE,  E.  C.  Colorado  River  and  Its  Utilization.  W.  S.  P.  395,  U.  S.  Geo- 
logical Survey. 

FOLLENSBEE  and  DEAN.  Water  Resources  of  the  Rio  Grande  Basin.  W.  S.  P. 
358,  U.  S.  Geological  Survey. 

HENSHAW  and  DEAN.  Surface  Water  Supply  of  Oregon.  W.  S.  P.  370,  U.  S. 
Geological  Survey. 

HENRY,  A.  J.  Climatology  of  the  United  States.  Bulletin  Q,  U.  S.  Weather 
Bureau. 

ALVORD,  J.  W.  and  BURDICK,  C.  B.  Relief  from  Floods.  McGraw-Hill  Book 
Co.,  New  York. 

HOYT  and  GROVER.     River  Discharge.     John  Wiley  &  Sons,  New  York 

-  Report  of  Special  Committee  on  Flood  Prevention.     Trans.  Am.  Soc.,  C.  E., 
Vol.  81. 

CHAMBERLAIN,  T.  C.  The  Requisite  and  Qualifying  Conditions  of  Artesian  Wells. 
Fifth  Annual  Report,  U.  S.  Geological  Survey.  Washington,  D.  C.,  1884. 

DARTON,  N.  H.  Preliminary  List  of  Deep  Borings.  U.  S.  Geological  Survey, 
Water  Supply  Paper  No.  61.  Washington,  D.  C.,  1902. 

ENGINEERING  NEWS.  Sewage  Purification  in  America.  New  York,  Feb- 
ruary 23,  1893;  July  18,  1894. 

HALL,  WM.  HAM.  Irrigation  in  Southern  California.  Part  II,  Annual  Report 
of  State  Engineer.  Sacramento,  1888. 

HAMLIN,  HOMER.  Underflow  Tests.  Water  Supply  Paper  No.  112,  U.  S.  Geo- 
logical Survey.  Washington,  D.  C.,  1905. 

HAY,  PROF.  ROBT.,  and  Others.  Geological  Reports  on  Artesian  Underflow  In- 
vestigations. Department  of  Agriculture,  Washington,  D.  C..  1892. 


64  WATER  SUPPLY 

HILL,  PROF.  ROBT.  T.,  and  Others.     Same  as  preceding. 

JACKSON,  Louis  D'A.    Hydraulic  Works.     W.  Thacker  &  Co.,  London,  1885. 

MANNING,  ROBERT.     Sanitary  Works  Abroad.     E.  &  F.  N.  Spon,  London,  1876. 

NETTLETON,  E.  S.  Artesian  and  Underflow  Investigations.  Department  of 
Agriculture,  Washington,  D.  C.,  1892. 

NEWELL,  F.  H.  Artesian  Wells  for  Irrigation.  U.  S.  Census  Bulletin  No.  193. 
Washington,  D.  C.,  1890. 

ORME,  S.  H.     Sewage  Irrigation.     Engineering  News.    New  York,  July  5,  1894. 

POWELL,  J.  W.  Artesian  Wells.  Part  II,  Eleventh  Annual  Report,  U.  S.  Geo- 
logical Survey.  Washington,  D.  C.,  1890. 

RAFTER,  GEO.  W.,  and  B/KER,  M.  N.  Sewage  Disposal  in  the  United  States. 
D.  Van  Nostrand  Co.,  New  York,  1894. 

SLIGHTER,  C.  S.  The  Rate  of  Movement  of  Underground  Waters.  U.  S.  Geo- 
logical Survey,  Water  Supply  Paper  No.  140.  Washington,  D.  C.,  1905. 

SPON,  ERNEST.  Present  Practice  of  Sinking  and  Boring  Wells.  E.  &  F.  N. 
Spon.  London,  1885. 

HAMLIN,  HOMER.  Water  Resources  of  the  Salmas  Valley,  California.  U.  S. 
Geological  Survey  Water-Supply  Paper  No.  89,  pp.  41,  42,  1904. 

McAoiE,  A.  G.  Rainfall  of  California.  California  Univ.  Pubs.,  vol.  i,  No.  4, 
p.  179,  Feb.  19,  1914. 


CHAPTER  VI 
EVAPORATION 

ALL  the  moisture  that  falls  from  the  heavens  must  at  some 
previous  time  have  been  taken  from  the  earth  by  some  form  of 
evaporation.  Conversely,  all  the  moisture  absorbed  by  the 
atmosphere  is  destined  to  fall  again  in  the  form  of  rain,  snow, 
hail,  etc.  Hence  in  the  long  run,  taking  the  earth  as  a  whole, 
evaporation  and  precipitation  are  practically  equal.  Evapora- 
tion depends  mainly  upon  the  wind  movement,  and  the  tem- 
perature and  relative  humidity  of  the  atmosphere.  It  also 
depends  of  course  upon  the  presence  of  moisture  to  evaporate. 

An  important  form  of  evaporation  is  the  transpiration  of 
moisture  from  the  leaves  of  plants,  in  the  process  of  growth. 
A  growing  crop  usually  transpires  several  times  as  much  moisture 
as  would  evaporate  from  the  same  soil  if  no  vegetation  were 
present.  Hence  the  importance  of  destroying  weeds  which 
not  only  consume  the  moisture  but  the  plant  food  needed  by  the 
crop. 

The  evaporation  from  the  surface  of  the  earth  varies  widely, 
but  the  precipitation  varies  still  more  widely.  In  a  region  of 
prevalent  fogs,  evaporation  is  low,  being  zero  during  a  fog, 
which  may  in  fact  precipitate  some  moisture.  Where  the 
atmosphere  is  very  warm  and  dry  the  potential  evaporation 
is  correspondingly  high.  In  a  hot  arid  region,  such  as  Southern 
Arizona,  and  Southeastern  California,  evaporation  is  at  its 
maximum,  and  may  reach  100  inches  per  annum.  In  the 
relatively  cool  and  foggy  regions  such  as  Labrador,  it  may  fall 
below  10  inches  per  annum. 

Evaporation  from  a  moist  soil  surface  may  be  two  or  three 
times  greater  than  from  a  water  surface,  by  reason  of  higher 
temperature,  if  exposed  to  the  direct  rays  of  the  sun.  Shading 

65 


66  EVAPORATION 

the  soil  decreases  the  evaporation  25  to  30  per  cent,  and  a 
mulch  of  straw,  leaves,  or  other  loose  material  still  more 
reduces  it. 

Experiments  in  Southern  California  by  the  Department  of 
Agriculture  showed  that  evaporation  from  the  bare  soil  could 
be  reduced  57  per  cent  by  a  3 -inch  mulch,  81  per  cent  by  a  6-inch 
mulch,  and  87.5  per  cent  by  a  g-inch  mulch. 

A  soil  mulch  with  similar  effect  may  be  produced  by  care- 
fully pulverizing  the  surface  soil,  or  in  other  words,  by  cultiva- 
tion. The  experiments  showed  a  saving  of  15  to  40  per  cent 
of  the  evaporation  by  such  cultivation. 

The  advantage  of  reducing  soil  evaporation  by  cultivation 
or  mulching  is  not  alone  the  saving  of  water  effected  but  there 
are  two  other  advantages  that  may  be  still  more  important. 

Rapid  evaporation  causes  rapid  rise  of  soil  moisture,  which 
brings  with  it  the  soluble  salts  carried  in  solution  by  the  soil 
water,  and  by  evaporation  leaves  the  salts  on  or  near  the  sur- 
face, where  they  may  in  time,  concentrate  to  a  harmful  extent. 

By  holding  the  soil  moisture  in  the  soil  until  it  can  be  taken 
up  by  plants,  it  is  given  time  to  dissolve  a  larger  amount  of  plant 
food,  and  thus  greatly  nourish  the  plants  when  absorbed  by  them ; 
whereas,  if  evaporation  is  given  full  play,  it  soon  exhausts  the 
soil  moisture,  and  fresh  water  must  be  more  often  applied,  so 
that  the  water  taken  by  the  plants  has  not  so  much  time  to 
collect  plant  food  and  is  less  conducive  to  plant  growth. 

i.  Measurement  of  Evaporation. — Several  methods  have 
been  devised  for  measuring  evaporation,  which  are  more  or 
less  satisfactory.  Elaborate  and  expensive  apparatus  has 
been  employed  in  evaporation  measurements  made  by  Mr.  Des- 
mond Fitzgerald,  chief  engineer  of  the  Boston  Water  Works, 
by  Mr.  Charles  Greaves  of  England,  and  others.  A  simple 
apparatus  and  one  quite  successful  as  a  means  of  measuring 
evaporation  is  that  employed  by  the  U.  S.  Geological  Survey. 
It  consists  of  a  pan,  Fig.  16,  so  placed  that  the  contained  water 
has  as  nearly  as  possible  the  same  temperature  and  exposure 
as  that  of  the  body  of  water  the  evaporation  from  which  is  to  be 
measured.  This  evapora ting-pan  is  of  galvanized  iron  3  feet 


MEASUREMENT  OF  EVAPORATION 


67 


square  and  18  inches  deep,  and  is  immersed  in  water  and  "kept 
from  sinking  by  means  of  floats  of  wood  or  hollow  metal.  It 
should  be  placed  in  the  water  in  such  position  as  to  be  exposed 
as  nearly  as  possible  to  its  average  wind  movements.  The  pan 
must  be  filled  to  within  3  or  4  inches  of  the  top,  that  the  waves 
produced  by  the  wind  shall  not  cause  the  water  to  slop  over,  and 


FIG.  1 6. — Evaporating-pan. 

it  should  float  with  its  rim  several  inches  above  the  surrounding 
surface,  so  that  waves  from  this  shall  not  enter  the  pan.  The 
device  for  measuring  the  evaporation  consists  of  a  small  brass 
scale  hung  in  the  center  of  the  pan.  The  graduations  are  on  a 
series  of  inclined  crossbars  so  proportioned  that  the  vertical 
heights  are  greatly  exaggerated,  thus  permitting  a  small  rise  or 
fall,  say  of  a  tenth  of  an  inch,  to  cause  the  water  surface  to  ad- 


68  EVAPORATION 

vance  or  retreat  on  the  scale  .3  of  an  inch.  By  this  device,  multi- 
plying the  vertical  scale  by  three,  it  is  possible  to  read  to  .01  of 
an  inch. 

In  1888  a  series  of  observations  were  made  with  the  Piche 
evaporometer  by  Mr.  T.  Russell  of  the  U.  S.  Signal  Service  to 
ascertain  the  amount  of  evaporation  in  the  West.  While  it  is 
probable  that  results  obtained  with  this  instrument  are  not  par- 
ticularly accurate,  comparisons  of  these  results  with  those  ob- 
tained by  other  methods  in  similar  localities  show  such  small 
discrepancies  that  they  may  be  considered  of  value  until  super- 
seded by  results  obtained  by  better  methods.  Observations 
were  made  with  this  instrument  in  wind  velocities  varying  from 
10  to  30  miles  per  hour,  from  which  it  was  discovered  that  with 
a  velocity  of  5  miles  an  hour  the  evaporation  was  2.2  times  that 
from  one  in  quiet  air;  10  miles  per  hour,  3.8  times;  15  miles, 
4.9  times;  20  miles,  5.7  times;  25  miles,  6.1  times;  and  30 
miles,  6.3  times. 

2.  Amount  of  Evaporation. — In  Table  X  is  given  the  amount 
of  evaporation  by  months  in  the  year  1888  in  various  sections 
of    the    West    as    derived    from    experiments    with    the    Piche 
apparatus. 

As  in  the  case  of  precipitation,  evaporation  decreases  with 
the  altitude  because  of  the  diminished  temperature  in  high  moun- 
tains. Experiments  were  made  to  determine  the  amount  of 
evaporation  in  different  portions  of  the  West  by  the  hydrog- 
raphers  of  the  U.  S.  Geological  Survey.  These  were  made  with 
the  evaporating-pan,  and  the  results  are  probably  (Table  XII), 
more  reliable  than  those  obtained  with  the  Piche  instrument. 
These  experiments  were  unfortunately  conducted  for  a  relatively 
short  space  of  time. 

3.  Evaporation  from  Snow  and  Ice. — Some  experiments  were 
conducted  at  the  Boston  Water  Works  to  determine  the  amount 
of  evaporation  from  snow  and  ice.     From  snow  it  amounted  to 
about  .02  of  an  inch  per  day,  or  nearly  2\  inches  in  an  ordinary 
season.     From  ice  it  amounted  to  .06  inch  per  day,  or  about 
7  inches  in  an  ordinary  season.     The  evaporation  from  snow 
is  greater  than  this  in  the  arid  regions  of  the  West,  especially 


EVAPORATION  FROM  SNOW  AND  ICE 


69 


on  barren  mountain-tops  such  as  those  in  Arizona,  Nevada,  and 
Utah,  where  they  are  exposed  to  the  wind  and  the  bright  sun- 
shine. 


TABLE  X.— DEPTH  OF  EVAPORATION,  IN  INCHES  PER  MONTH  IN 

1887-88 


Stations  and  Districts. 

00 
00 
."OO 

c  <-< 

OJ 

1  —  ) 

OO 

.00 

I" 

•gs 

fc.00 

a  M 

00 

a  M 

00 
-00 

rtM 

|I 

.00 

*3  M 

I—  1 

bO<£ 

TOO 
C/J 

00 

r  oo 
"o  " 

o 

roo 

3" 

.00 

"12 

0) 

Q 

13 

<0 

NORTHERN  SLOPE: 
Fort  Assiniboine..  .  . 
Fort  Custer  
Fort  Maginnis  
Helena   
Poplar  River  
Cheyenne  
North  Platte  
MIDDLE  SLOPE: 
Colorado  Springs.  .  . 
Denver  
Pike's  Peak  

0.8 

0.6 
i  .  i 
1.  1 
0.4 
3-3 
0.8 

3-0 

2.8 
2  .  I 

I  .  2 

1.5 

1.4 

3.6 
0.8 

5-7 
1.8 

3-3 
3-7 
1  .3 

I  .  2 

1.3 

I  .  I 

2.  I 

0.8 
4-0 
1.8 

4.1 
3-5 
i  .  5 

3-1 
5-4 
3-3 
6.1 

2.7 

8.2 

5-4 

6.7 
7.6 
2  I 

4-  i 
6.8 

3-2 

4-3 
4-9 
5.2 
3-9 

It 

I    8 

4.2 
4-9 
4.6 
5-5 
5.7 
10.4 
•6.9 

4-3 
10.  S 
I  9 

6.8 
9.6 
6.8 
7.2 
6.0 
8.0 
6.0 

6.7 
8.3 
3   o 

5.5 

8.0 
4.6 
7-7 
4.8 
7-7 
4.8 

7-2 
8.5 
4  o 

4.8 
6.1 
3.8 
6.4 
4-4 
8.6 
3-7 

6.8 
6.  i 

3-5 
3-4 

2.8 

4-3 
2.5 
.  5-8 

2.8 

4.6 
4-9 
2   3 

2.5 

2.9 

2.0 

3-0 
1.7 
6.  i 

2-3 

4-2 
4-2 

2    8 

I.  I 
1.5 
i..  i 

2.  I 

0.7 
3-5 
1.  1 

2.9 
3-1 

39-5 
52.0 
35-8 
53-4 
35-4 
76.5 
41-3 

59-4 
69.0 
26  8 

Concordia  

1.3 

2.8 

1.8 

4.8 

4-3 

5-7 

7-3 

5-2 

6  6 

4-3 

4-5 

3.4 

47.2 

Fort  Elliott   
SOUTHERN  SLOPE;: 
Fort  Sill  
Abilene  

1.3 

1.6 

T     8 

I  .9 

2.O 
1  .  7 

3-2 

2.6 
3  •  I 

5-1 
3-8 

4.  2 

5-4 

4.0 
5  •  o 

8.2 

4-4 
5  8 

7-6 

4.8 
9   5 

6.2 

7-5 
7   5 

5-4 
5-  i 

6    2 

4-7 

4.2 
4  5 

4.2 
4.1 

2.  2 
2.0 

54-0 
55-4 

46.  i 

Fort  Davis  
Fort  Stanton  
SOUTHERN  PLATEAU: 
El  Paso  
Santa  Fe  
Fort  Apache  
Fort  Grant  
Prescott 

5-4 
3-9 

4.0 
3-0 

2.6 

5-2 

I   4 

5-7 
3-9 

3-9 

3-4 
3-0 
4.8 

2    8 

6.7 

5-2 

6.0 
4.2 
3-6 
6.4 
3  6 

8.5 
7-3 

8.4 
6.8 
6.8 

9-2 

II.  0 

9-5 

10.7 
8.8 
9-4 

10.2 

6   ° 

12.0 

10.9 

13.6 
12.9 
9-1 
13-8 
8  i 

11.4 
9.4 

9.4 
9.2 

7-1 
12.4 
6  6 

9.0 
ii.  6 

7-7 
9.8 
6.7 
10.5 

6   s 

5-9 
3-9 

5-6 
6.6 
5-3 
9.0 

14    7 

5-2 
4.0 

5-2 
6.7 
5.2 
7-9 

5-7 
3-6 

4.6 
5-7 
4.1 
7.2 

-y     A 

4-9 
3-8 

2.9 

2.7 
2.6 

4.6 

96.4 
76.0 

82.0 
79-8 
65-5 
IOI.2 

Yurna  

4.  4 

5    2 

9  6 

9  6 

12  6 

u.5 

8    2 

C      C 

4  6 

Keeler 

4  ° 

6  3 

8  7 

12    8 

8   8 

4  8 

MIDDLE  PLATEAU: 
Fort  Bidwell 

o   8 

8 

i  8 

4  6 

8   8 

8    i 

4  6 

Winnemucca  
Salt  Lake  City  
Montrose  
Fort  Bridger  
NORTHERN  PLATEAU: 

0.9 
1.8 
1.8 
1.6 

i   6 

.8 

.7 
-5 

6.2 

3-6 
3-7 

2.7 

3  8 

9-1 

7-2 

6.2 

4-3 
6  i 

9-3 
6.9 
7-0 
4-3 

6  5 

10.  I 

8.9 
II.  i 
6.5 

6  6 

II.  5 
9.2 

IO.2 

7-7 

12.0 

10.7 
8.3 
6.8 

9-9 
9-6 

6.9 
5-6 

6.6 
6.5 

5-2 

4.2 

3-7 

5-0 
3-4 

5-2 

1.8 

2.3 
2.0 

4-7 

T  8 

40.  y 
83-9 
74-4 
68.3 
56.1 

Spokane  Falls.  .  . 
Walla  Walla 

0-7 
i    i 

.7 

3  6 

4-4 

6  2 

5-4 

4-4 

7-7 

6.4 

3-8 

2.5 

•I 

J  .0 

1.4 

42.8 

N.  PACIFIC  COAST: 
Fort  Canby 

I     2 

I  8 

2    8 

I    8 

I    8 

I    8 

: 

Olympia  
Tatoosh  Island  
Roseburg  
MID.  PACIFIC  COAST: 
Red  Bluffs  
Sacramento     
S.  PACIFIC  COAST: 
Fresno  
Los  Angeles  
San  Diego  

1.3 

1.2 
I  .2 

3-0 

1.8 

1.8 

2.3 
2.9 

.  2 

.6 

4.6 
3-1 

2.8 
2.0 
2.7 

1.8 
1.8 

2.7 

5-4 
3-7 

3-0 

2.8 

2.5 

2.5 
1.4 
3-9 

6.1 
4-3 

5-6 

3-4 

2.7 

4.1 
1.8 
4-7 

7.0 
4.2 

6.0 
3-0 
3-3 

3-3 
1.8 
3-5 

6.9 
5-6 

7.0 
3-8 

2.8 

3.2 

1.4 
5-4 

II  .0 

5-9 

9.  I 

3-2 

3.2 

3-  i 

1.4 
4-7 

10.7 
5.6 

IO.  2 
3-5 
3-3 

2.4 
I  .4 
5-0 

IO.  I 

6.5 

7.6 
3-  1 
2.9 

1.5 

1.6 

3-2 

10.5 
7.3T 

6.7 
4.1 
4-3 

::: 

3-9 

3-8 
3-0 
3-2 

i  .  i 

1.4 

1.6 

3-6 

2.4 

2.  2 
3.0 
3-7 

26.8 
18.1 
39.2 

84.8 
54-3 

65.8 
37.3 

37.5 

4.  Evaporation  from  Earth. — The  amount  of  evaporation 
from  earth  in  the  West  is  a  doubtful  quantity.  Important  ex- 
periments bearing  on  this  were  made  in  England  between  1844 


70 


EVAPORATION 


and  1875.  From  these  it  appears  that  the  amount  of  evaporation 
from  ordinary  soil  is  about  the  same  as  that  from  water,  some- 
times exceeding  it  a  little  and  sometimes  being  a  trifle  less,  though 


TABLE  XI.— DEPTH  OF  EVAPORATION  PER  MONTH,  IN  INCHES 


'a 

*j 

s 

Place 

3 
C 

£ 

ji 

a 

r^ 

cd 

8 

>? 

1 

cx 

^ 

> 

0 

0> 

I* 

c 

cs 
1—  1 

<o 

s 

O, 

3 

3 
t—i 

< 

"o 

O 

o 

& 

1889 

Fort  Douglas,  near 

10.5 

5.7 

4.9  i  .0 

1890 

Salt    Lake    City, 

3-7 

4.1 

5-1 

7.6    6.5 

4.6 

2.  I 

1.2 

1891 

Utah  

3-2 

4.8 

5-2 

7-6 

6.5 

5-2 

2.5 

1.4 

1892 

j 

40.0 

1.6 

i.S 

s'.i 

2.3 

4.1 

5-3 

6.5 

7-3 

5.2J2.I 

1.61.1 

1889  Xephi  and  Provo  
1  889!  Cherry  Creek,  Colo  
1889  Canyon  City,  Colo  

.... 

:::::: 

3-9 
8.1 

5-0 
7-9 

4.6 
8.6 

7  •  I 

2.9  3-3 

2.5 

2.2 

1890 

/  ' 

anyon  City,  Colo.  .  .  . 

3.84.8 

5-2      7-3 

'6.'o  

'.'.'.'. 

1889 

...... 

lO.QJIO.  7 

9.611.4 

9.2 

6^8 

4.6  2.9 

1890 

Fort  Bliss,  near  El 

2\0 

2.0 

7-0 

7-3 

lO.SIn  .7 

9.6 

7.6 

3.7 

3-0 

1891 

Paso,  Texas  

2-7 

2.9 

5-5 

7-4 

1892 

91.6 

2.4 

3.2  6.0 

7-5 

10.  0 

13.0)12.5 

Ii.  9 

9-2 

6.8 

4.2 

2.9 

1889 

Tempe,  Ar  z  

1 

13-7 

14.1 

II  .06.4 

4.4 

1890 

t  *                         * 

...  1  ... 

5^8 

5-5 

5  -6 

6.6 

5.8  5-2 

4.6 

3  •  2 

I  80  I 

85.5 

3  •  9 

3.61^.7 

4  •  2 

1890  Florence       '     

5.8 

8.2 

ii.  5 

13-5 

1  004 

Y 

Ljina^          '     

80.0 

1890 

.... 

2.0 

2^8 

7-2 

8.5 

7-2 

7-1 

4-3 

3.6 

2.5 

generally  averaging  about  3  inches  less  than  the  corresponding 
evaporation  from  water  surfaces.  The  evaporation  from  sandy 
surfaces  was  found  to  be  only  about  one-fourth  to  one-fifth  that 
from  water.  Thus  in  the  observations  of  1873,  where  the  mean 
evaporation  from  water  was  20.4  inches,  that  from  earth  was 
17.9  inches  and  from  sand  3.7  inches.  Soil  cover  of  any  kind 
greatly  affects  the  amount  of  evaporation.  Assuming  the  evap- 
oration from  water  is  i.oo,  Prof.  B.  E.  Fernow  gives  it  for  bare 
soil  0.60;  sod  1.92;  cereals  1.73;  and  forest  1.51.  Evaporation 
from  ground  covered  with  forest  leaves  is  10  to  15  per  cent  and 
sand  33  per  cent  less  than  from  bare  soil. 

5.  Effect  of  Evaporation  on  Water  Storage. — The  need  of 
water  storage  for  irrigation  in  the  West  chiefly  occurs  in  July, 
August  and  September.  Little  rain  falls  in  the  arid  region 
during  this  period,  so  that  comparatively  little  of  the  loss  of 
evaporation  is  replaced  by  rain.  As  an  example,  in  Central 
California,  where  the  average  rainfall  during  these  months 
amounts  to  a  trifle  less  than  i  inch,  the  evaporation  during 
the  same  period  amounts  to  about  21  inches.  The  total  resultant 


EFFECT  OF  EVAPORATION  ON  WATER  STORAGE  71 

deficiency  chargeable  to  evaporation  is  about  20  inches.  Storage 
reservoirs  in  the  West  are  frequently  at  high  altitudes  in  the 
mountains,  where  evaporation  is  less  than  in  the  hot  lowlands. 
At  Arrowhead  reservoir,  CaL,  altitude  5160  feet,  the  measured 
evaporation  averages  36  inches  per  annum,  of  which  about 
40  per  cent  occurs  between  May  and  August,  the  irrigation 
season. 

The  erratic  stream  flow  in  arid  regions  makes  it  desirable 
to  store  the  waters  of  abundant  years  for  use  in  dry  years, 
and  these  extremes  are  often  many  years  apart,  and  the  water 
held  in  storage  is  thus  subject  to  evaporation  throughout  the 
interval.  In  hot  countries,  where  the  rate  of  evaporation  is 
high  this  places  a  serious  handicap  on  the  complete  utilization 
of  the  water  supply. 

In  1909  and  1910,  the  U.  S.  Weather  Bureau  made  a  series 
of  careful  observations  of  evaporation  at  several  stations,  the 
results  of  which  are  given  in  table  XII,  page  72. 

REFERENCES   FOR  CHAPTER  VI 

WIDTSOE,  J.  A.     Factors  Influencing  Evaporation  and  Transpiration.     Bulletin 

No.  105.     Utah  Agricultural  College,  Logan,  Utah. 

BUCKLEY,  R.  B.  Irrigation  Works  in  India  and  Egypt.  E.  &  F.  N.  Spon,  London. 
FORTIER,  SAMUEL,  livaporation  Losses  in  Irrigation  and  Water  Requirements 

of  Crops.     Bulletin  No.  177.     Office  of  Experiment  Stations.     U.  S.  Dept.  of 

Agriculture. 
BIGELOW,  F.  H.     Records  of  Evaportaion  at  23  Different  Stations.     Engineering 

News,  vol.  63,  No.  24,  June  16,  1910,  New  York. 
DURYEA,   EDWIN,  JR.,  and  HAEHL,  H.   L.     Evaporation  from  Lake  Conchos, 

Mexico.    Trans.  Am.  Soc.  C.  E.,  vol.  80,  New  York. 


72 


EVAPORATION 


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c      co 


O      OOO      u->OOO      O      >O>O      ON^CO 
CN       CM       LOlO-^-O       M       <N       CI       CO     IO     IO 


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t^    ir>    ir>    -Ln    ir>    u-) 


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-  • 


CHAPTER  VII 
PUMPING  FOR  IRRIGATION 

THE  practice  of  lifting  water  from  a  lower  to  a  higher  level 
for  use  in  irrigation  is  doubtless  as  old  as  the  art  of  irrigation 
itself,  and  was  probably  the  first  form  oi  irrigation  tried.  In 
China,  India,  and  other  Oriental  countries  it  is  still  customary 
to  irrigate  lands  higher  than  the  canals  which  conduct  the  water 
to  them,  lifting  it  a  few  feet  by  human  or  animal  power.  Many 
various  devices  of  a  primitive  nature  are  still  employed  for 
this  purpose.  They  are  of  course  possible  only  where  the  lift 
is  slight  and  labor  very  cheap. 

The  familiar  processes  of  pumping  water  for  stock  and 
domestic  farm  use,  and  on  a  larger  scale  for  a  city  water  supply 
is  apt  to  mislead  many  persons  when  considering  problems  of 
pumping  for  irrigation,  owing  to  the  relatively  large  quantity 
of  water  required  for  irrigation  and  the  corresponding  low  unit 
value  of  irrigation  water.  For  example  a  city  of  30,000  inhabi- 
tants, covering  say  1000  acres,  might  well  afford  to  expend  a 
million  dollars  or  more  for  a  domestic  water  supply,  while  an 
equal  quantity  of  water  would  be  necessary  to  irrigate  1000 
acres  properly,  and  an  expenditure  of  one-tenth  that  amount 
for  the  water  supply  might  for  this  purpose  be  prohibitive. 
In  other  words,  the  value  of  water  for  domestic  purposes  is 
often  more  than  ten  times  as  great  as  the  value  of. the  same 
quantity  of  water  for  irrigation.  In  fact,  domestic  water  supply 
being  indispensable,  it  must  be  obtained  at  any  cost,  and  the 
value  of  irrigation  water  is  limited  by  the  value  of  the  crops 
raised,  in  which  it  is  only  one  element  of  cost. 

Pumping  for  irrigation  is  therefore  generally  feasible  only 
where  the  water  supply  is  ample,  the  lift  moderate  and  power 

73 


74  PUMPING  FOR  IRRIGATION 

cheap.  Exceptions  to  this  combination  occur  only  where  the 
products  of  irrigation  are  exceptionally  valuable. 

i.  Ground-water  Supply. — Where  an  irrigation  supply  is  to 
be  obtained  from  the  ground-water  by  means  of  wells,  a  careful 
study  must  be  made  of  the  quantity  of  water  that  can  be  made 
available  from  each  well,  and  also  the  total  supply,  and  the 
system  carefully  planned  to  accord  with  the  facts  developed 
by  that  study.  One  of  the  commonest  errors  made  in  irrigation 
engineering  is  the  overestimate  of  the  dependable  supply  of 
water  from  a  well  of  given  design.  The  total  supply  of  ground 
water  available  in  a  given  locality  is  also  frequently  over- 
estimated, and  seldom  underestimated. 

The  ground-water  supply  depends  not  only  on  the  presence 
of  ground  water  at  the  site  of  the  well,  but  also  upon  the  facility 
with  which  additional  water  reaches  the  well  as  water  is  removed 
by  pumping,  and  this  in  turn  depends  upon  the  size  of  the  open- 
ings between  the  soil  particles  surrounding  the  well.  If  the 
water-bearing  material  is  coarse  sand  or  gravel  in  which  the 
spaces  occupied  by  water  are  relatively  large,  the  water  will 
move  toward  the  well  with  comparative  freedom  as  the  water 
level  in  the  well  is  lowered,  and  the  yield  from  the  well  may  be 
large,  while  if  the  water-bearing  medium  is  clay  or  fine  silt  in 
which  the  interstices  filled  with  water  are  very  minute,  the 
friction  of  moving  is  so  great  that  the  water  moves  through  it 
with  extreme  slowness,  so  that  the  yield  of  each  well  is  very 
small,  although  the  total  voids  in  the  clay  or  silt  may  be  and 
usually  are  greater  in  volume  than  those  in  coarse  sand  or 
gravel. 

The  pore  space  in  soils  of  the  arid  region  will  average  nearly 
50  per  cent,  varying  from  about  40  per  cent  for  clean  sand,  to 
55  per  cent  for  clay.  A  well-graded  mixture,  however,  contains 
much  less  open  space,  and  may  have  below  30  per  cent.  Each 
particle  of  soil  under  field  conditions  is  enveloped  by  a  very 
thin  film  of  moisture  which  will  not  drain  out,  and  can  be  driven 
off  only  by  heat.  The  area  of  these  surfaces  is  6  or  7  times  as 
great  in  clay  as  in  coarse  sand,  and  the  number  of  particles  is  in 
similar  ratio. 


WINDMILLS  75 

2.  Windmills. — A  great  deal  of  irrigation  has  been  done 
in  primitive  systems  by  the  employment  of  the  power  of  the  wind, 
and  this  is  still  in  extensive  use  for  lifting  water  from  wells 
for  domestic  use,  stock  water,  and  to  irrigate  gardens  and  small 
orchards.  Wind  power  comes  next  to  animal  power  not  only 
historically,  but  in  cost.  Although  the  power  is  free,  pumping 
by  windmills  is  on  the  average  more  expensive  than  any  other 
methods  except  those  employing  animal  power.  This  is  due  to 
the  relatively  small  amount  of  power  developed  by  any  one 
unit,  the  inconstancy  of  the  wind,  and  the  large  amount  of 
attention  and  repairs  required  by  the  windmills.  For  these 
reasons,  the  cost  of  pumping  water  for  irrigation  by  windmills 
is  generally  prohibitive  except  for  intense  cultivation  of  small 
tracts  from  which  large  returns  are  expected,  and  in  addition 
the  lift  must  be  low  and  other  conditions  favorable.  Even  then 
the  cost  is  seldom  less  than  $100  per  unit  for  first  installation  of 
well,  storage  tank  and  pumping  machinery,  and  may  reach  several 
times  that  amount.  Besides  this  the  cost  of  maintenance  is 
high,  averaging  over  $10  per  year,  while  the  area  which  one 
windmill  can  serve  is  generally  less  than  an  acre,  and  may 
be  much  less. 

Windmills  of  standard  make  can  be  purchased  of  any  large 
dealer  in  agricultural  implements,  but  representations  concern- 
ing  the  power  to  be  developed  by  them  should  be  usually  dis- 
counted to  eliminate  optimistic  assumptions,  and  liberal  allow- 
ance should  be  made  for  the  inconstancy  of  the  wind. 

Notwithstanding  its  relatively  high  cost  a  windmill  plant 
may  be  the  most  advisable  and  economical  plant  where  the 
requirements  or  the  water  supply  limit  the  irrigation  to  less 
than  one  acre.  Many  farms  on  the  great  plains  devoted  mainly 
to  grazing  or  dry  farming  are  thus  furnished  with  a  reliable 
supply  of  vegetables  and  small  fruits  which  contribute  materially 
to  the  support  and  the  health  of  the  family. 

Windmills  are  extensively  used  in  the  San  Joaquin  valley  in 
California,  on  the  great  plains  east  of  the  Rocky  Mountains 
and  in  other  portions  of  the  West,  for  pumping  water  for  irriga- 
tion. The  chief  objection  to  windmills  for  this  purpose  is  their 


76 


PUMPING  FOR  IRRIGATION 


unreliability,  as  they  are  wholly  dependent  upon  the  force  of 
the  wind  for  their  operation.  This  objection  is  not  so  serious 
on  the  great  plains  between  the  Rocky  Mountains  and  the 
Mississippi  River,  where  there  is  generally  a  wind  to  keep  mills 
turning.  In  most  other  places  they  are  less  certain  in  their 
action,  and  may  fail  the  farmer  at  the  very  time  when  he  is  most 
in  need  of  a  water-supply. 

Because  of  their  uncertainty  of  operation,  windmills  should 
never  be  used  for  purposes  of  irrigation  without  providing  as  an 
adjunct  an  ample  tank  or  reservoir  for  the  storage  of  sufficient 
water  to  irrigate  a  considerable  area.  Ample  capacity  should  be 
provided  to  store  the  water  of  several  days'  pumping  when 
irrigation  may  not  be  necessary.  This  storage  capacity  may  be 
obtained  by  using  one  of  the  various  forms  of  elevated  tanks 
which  are  supplied  by  windmill  makers;  or,  if  the  windmill 
can  be  located  at  a  high  point  on  the  farm,  an  artificial  reservoir 
may  be  excavated  at  this  point  and  suitably  lined,  which  shall 
have  capacity  to  contain  a  larger  amount  of  water. 

It  requires  on  an  average  a  wind  velocity  of  5  or  6  miles  an 
hour  to  drive  a  windmill,  and  on  an  average  winds  exceeding 
this  velocity  are  to  be  had  during  only  eight  hours  per  day. 
Hence,  about  two-thirds  of  the  total  time  is  lost  for  work.  The 
reports  of  the  U.  S.  Weather  Bureau  indicate  that  the  average 
wind  movement  of  the  entire  country  is  5769  miles  per  month, 
or  about  8  miles  per  hour. 

These  averages  are  somewhat  exceeded  on  the  Great  Plains, 
where  the  average  hourly  velocity  is  10  miles.  The  following 
tables  give  roughly  the  force  of  the  wind  for  ordinary  velocities: 

TABLE  XIII.— WIND   VELOCITY  AND   POWER 


Miles  per 
Hour 

Feet  per 
Second 

Pressure  per 
Sq.  Ft.  in  Lbs. 

Miles  per 
Hour 

Feet  per 
Second 

Pressure  per 
Sq.  Ft.  in  Lbs. 

6 

7  •  5 

.  12 

30 

44.0 

4-4 

10 

14-7 

•  5 

35 

51-3 

6.0 

15 

22.0 

i  .  i 

40 

58.8 

7-9 

20 

29-3 

2  .0 

45 

66.0 

IO.O 

25 

36.7                      3-i 

50 

73-3 

12.3 

WINDMILLS 


77 


TABLE  XIV.— ENERGY  OF  WIND  ACTING  UPON  A  SURFACE  OF  100 

SQUARE  FEET 


Velocity  of  Wind 

At  Sea-level 

At  1000  Ft.  above 
Sea-level 

At  2000  Ft.  above 
Sea-level 

Miles  per  Hour. 

H.P. 

H.P. 

H.P. 

5 

0-0835 

0.0780 

0.0724 

IO 

0.6683 

0.6237 

0.5792 

15 

2.2550 

2.1050 

i  -'9550 

20 

5-3470 

4.9900 

4.6340 

25 

10.4400 

9  .  7460 

9.0500 

30 

18.0400 

16.8400 

15.6400 

The  following  table  is  derived  from  Mr.  A.  R.  Wolff's  excel- 
lent work  on  the  windmill,  and  shows  the  capacity  and  economy 
of  an  experimental  windmill  having  various  diameters  of  wheels, 
with  an  assumed  average  velocity  of  wind  of  16  miles  per  hour 
and  with  eight  hours  per  day  as  the  average  number  of 
days  during  which  the  results  given  may  be  obtained. 

TABLE  XV.— CAPACITY   OF   WINDMILLS 


GALLONS  OF  WATER  RAISED  PER  MINUTE  TO  AN 

Horse- 

Size  of 

Revolutions 

ELEVATION  OF 

Wheel, 

of 

Devel- 

Ft. 

Wheel 

25  Ft. 

50  Ft. 

75  Ft. 

ioo  Ft. 

150  Ft. 

200  Ft. 

oped 

10 

60  to  65 

19.2 

9.6 

6.6 

4-7 

O.  12 

12 

55  to  60 

33-9 

17.9 

n.  8 

8-5 

5-7 

0.21 

14 

50  to  55 

45-i 

22.6 

15-3 

II  .  2 

7-8 

4-9 

0.28 

16 

45  to  50 

64.6 

31.6 

19-5 

16.1 

9-8 

8.0 

0.41 

18 

40  to  45 

97-7 

52.2 

32.5 

24.4 

17-5 

12.  2 

0.61 

20 

35  to  40 

124.9 

63.7 

40.8 

31.2 

19-3 

15-9 

0.78 

25 

30  to  35 

212.4 

107.0 

71.6 

40.7 

37-3 

26.7 

i-34 

In  designing  a  windmill  for  pumping,  two  things  have  to  be 
considered — the  torque,  or  statical  turning  moment,  and  the 
speed  of  the  wheel  in  relation  to  that  of  the  pump.  The  former 
should  be  as  large  as  possible  so  that  the  mill  will  start  with  the 
faintest  wind,  and  the  latter  must  not  be  too  fast  for  the  pumps 
in  a  small  mill  or  too  slow  in  a  large  one.  Hence  the  size  of  a 


78 


PUMPING  FOR  IRRIGATION 


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Outer  diameter  of  sail-wheel,  feet  
Inner  diameter  of  sail-wh£el,  feet  
Gross  area  of  sail-  wheel,  square  feet  
Weather  angle  at  outer  ends  of  vanes  
Diameter  and  stroke  of  pump,  inches  
Average  head  of  water  during  tests,  feet  

AT  MAXIMUM  EFFICIENCY 

Velocity  of  wind,  miles  per  hour  
Velocity  of  mill,  revolutions  per  minute  
Actual  horse-power  
Horse-power  per  100  square  feet  of  gross  area  
Maximum  net  efficiency,  per  cent  „  

IN  100  AVERAGE  HOURS,  CALM  LOCALITY 

Average  quantity  of  water  lifted,  gallons  per  hour. 
Average  continuous  horse-power  developed  per  100 
Average  continuous  gross  horse-power  developed  .  . 
Average  net  efficiency,  per  cent  

IN  100  AVERAGE  HOURS,  WINDY  LOCALITY 

Average  quantity  of  water  lifted,  gallons  per  hour. 
Average  continuous  horse-power  developed  per  100 
Average  continuous  gross  horse-power  developed  .  . 
Average  net  efficiency;  per  cent  

WATER-WHEELS  79 

mill  is  an  important  element  in  the  arrangement  of  its  vanes. 
The  angle  between  any  portion  of  a  vane  and  the  plane  of  the 
wheel  is  termed  the  weather  angle,  and  to  obtain  the  greatest 
torque  at  starting  the  weather  angle  should  be  the  complement 
of  the  best  incidence  angles,  or  between  70  and  55  degrees.  In 
practice  it  is  found  that  the  weather  angle  is  never  as  great  as 
this,  being  in  the  best  examples  about  43  degrees. 

Table  XVI  gives  the  results  of  Mr.  J.  A.  Griffiths',  experi- 
ments for  the  five  American-made  windmills  tested. 

3.  Water-wheels. — Water-wheels  may  be  subdivided  into 
two  classes:  (i)  vertical  water-wheels  and  (2)  horizontal  water- 
wheels.  Of  the  former  we  have  the  more  common  of  the  old- 
fashioned  wheels: 

1.  Undershot  water-wheels. 

2.  Breast- wheels. 

3.  Overshot  water-wheels. 

4.  Hurdy-gurdies. 

5.  Tangential  water-wheels. 

The  latter  is  a  modern  adaptation  of  the  old-fashioned 
hurdy-gurdy,  and  is  properly  an  impulse  wheel.  Horizontal 
wheels  are  turbines  of  various  types,  and  in  these,  like  vertical 
wheels,  water  may  act  both  by  pressure  or  impulse,  or  by  a 
combination  of  the  two. 

a.  Undershot  Water-wheels. — The  word  water-wheel  is  usually 
applied  to  the  various  old-fashioned  vertical  wheels,  undershot, 
breast,  and  overshot  wheels.  Undershot  wheels  may  be  classi- 
fied as  midstream  wheels,  the  common  "undershot  wheels,  and 
Poncelet  wheels.  In  midstream  wheels  the  motive  power  is 
due  to  the  velocity  or  impulse  of  the  current  of  water  in  the* 
stream  in  which  the  wheel  is  set,  and  such  wheels  are  employed 
almost  exclusively  for  the  elevation  of  water  for  irrigation. 
They  are  very  simple  in  construction  and  operation,  and  may  be 
advantageously  employed  wrhere  water  is  abundant,  even  in 
streams  having  low  velocity  of  flow. 

In  rivers  where  the  water-level  fluctuates,  the  axle  of  the 
wheel  is  made  movable  on  its  supports  to  render  it  capable 
of  being  raised  or  lowered  at  pleasure  to  suit  the  height  of  water- 


80  PUMPING  FOR  IRRIGATION 

level,  and  this  is  effected  by  resting  one  or  both  extremities 
of  the  axle  on  floats.  The  horse-power  of  a  midstream  wheel 
may  be  calculated  by  the  following  formula  from  Mr.  P.  R. 
Bjorling: 

HP  =  v-v 


in  which  v  is  the  velocity  of  the  stream  in  feet  per  second,  vi 
the  mean  velocity  of  the  float-boards  in  feet  per  second,  and 
A  the  immersed  area  of  the  float-boards  in  square  feet. 

Numerous  wheels  of  this  class  have  been  successfully  em- 
ployed in  pumping  water  for  irrigation  in  various  portions  of 
the  West.  In  some  cases  these  wheels  have  attached  to  their 
outer  rim  a  row  of  buckets  (Fig.  20),  which  dip  into  the  water 
as  the  wheel  revolves,  are  thus  filled,  and  then  as  they  reach 
the  upper  portion  of  their  revolution  spill  their  contents  into 
a  trough  which  leads  to  the  irrigating  ditch.  Other  forms 
of  midstream  wheels  are  connected  by  means  of  gearing  or 
belting  with  pumps  which  elevate  the  water  for  irrigation. 

The  average  diameter  of  the  midstream  water-wheel  of 
the  West  varies  from  10  to  20  feet  and  the  length  of  the  blade 
of  the  paddle  from  6  to  10  feet.  Some  wheels  of  this  variety 
but  of  large  size  have  been  successfully  employed  —  notably 
on  the  Green  River  in  Colorado  which  are  from  20  to  30  feet 
in  diameter.  These  are  hung  on  wooden  axles  5  inches  in 
diameter,  while  their  paddles  dip  2  feet  into  the  stream.  On 
their  outer  circumference  are  buckets  of  wood  having  an  air- 
hole in  the  bottom  closed  by  a  suitable  leather  flap-valve  which 
permits  the  bucket  to  fill  rapidly  by  forcing  out  the  air.  These 
buckets  are  6  feet  in  length  and  4  inches  square,  and  have  a 
capacity  of  a  little  less  than  a  cubic  foot  each.  The  largest 
of  the  wheels  on  the  Green  River  have  16  paddles  and  lift  10 
cubic  feet  of  water  per  revolution,  and  as  they  make  two  revolu- 
tions a  minute,  though  they  spill  a  large  portion  of  their  con- 
tents, each  wheel  handles  about  4000  cubic  feet  per  day,  or 
approximately  i/io  of  an  acre-foot. 

Common  undershot  water-wheels,  as  distinguished  from 
midstream  wheels,  are  the  best  where  a  fall  of  convenient  height 


WATER-WHEELS  81 

cannot  be  obtained,  and  the  velocity  of  the  water  is  yet  relatively 
great.  These  are  confined  in  a  channel  which  is  made  about 
the  width  of  the  wheel  and  is  wider  at  the  inlet  than  at  the  wheel 
so  as  to  give  freedom  of  access  to  the  water  and  to  increase  its 
velocity.  These  wheels  operate  most  satisfactorily  where  the 
fall  is  from  \  to  2  feet  in  the  course  of  the  race.  The  paddles 
are  similar  to  those  for  midstream  wheels,  though  sometimes 
they  are  curved  and  of  iron.  The  number  of  float-boards  or 
paddles  for  such  a  wheel  may  be  determined  by  the  formula: 


in  which  n  is  the  number  of  float-boards  and  d  the  diameter  of 
the  wheel.  These  wheels  vary  in  diameter  from  10  to  20  feet, 
and  are  usually  constructed  of  from  30  to  40  paddles,  varying 
from  1  1  to  i\  feet  in  depth,  their  length  being  from  3  to  6 
feet. 

Poncelet  wheels  act  rather  on  the  turbine  principle,  their 
paddles  being,  curved.  They  are  usually  immersed  to  the 
height  of  their  axes,  and  the  water  is  screened  from  them  with 
the  exception  of  a  few  inches  near  their  under  surface,  so  that 
it  impinges  by  impulse  against  the  under  side  of  the  wheel  and 
acts  much  as  does  a  turbine. 

Breast-wheels  are  placed  where  there  is  a  considerable  fall 
in  a  manner  similar  to  Poncelet  wheels,  so  that  the  level  of 
water  is  about  at  the  height  of  their  axes.  They  have  usually 
curved  paddles  or  buckets,  and  the  water  impinges  against 
them  both  by  weight  and  impulse  at  a  point  below  the  axial 
line. 

b.  Overshot  Water-wheels.  —  Overshot  wheels  are  more  economi- 
cal than  undershot  wheels  in  their  use  of  water,  and  are  there- 
fore employed  where  water  is  scarce.  In  these  the  water  is 
delivered  above  the  wheel  by  means  of  a  flume,  race,  or  pen- 
stock, and  they  are  so  constructed  that  the  water  may  be  de- 
livered either  on  the  near  or  the  far  side  of  the  wheel,  according 
to  the  arrangement  of  the  outlet  gates  controlling  the  supply. 


82  PUMPING  FOR  IRRIGATION 

On  the  outer  circumference  of  the  overshot  wheel  is  a  series  of 
buckets  into  which  the  water  pours  and  by  its  weight  causes 
the  wheel  to  revolve.  As  the  wheel  turns  each  bucket  fills 
as  it  passes  the  inlet  and  empties  as  it  approaches  the  bottom, 
so  that  on  one  side  are  always  a  certain  number  of  buckets 
filled  with  water.  In  order  to  lose  as  little  of  the  fall  as  possible 
the  bottom  of  the  wheel  should  approach  close  to  the  lower 
water  surface,  but  should  not  dip  into  it,  as  by  drowning  the 
wheel  its  power  is  diminished. 

The  buckets  of  overshot  wheels  may  be  made  of  straight 
boards  or  sheets  of  metal  having  two  or  three  bends  in  them,  or 
may  be  curved.  The  number  of  buckets  may  be  calculated  by 
the  following  formula  given  by  Bjorling:  For  wheels  from  12 
to  20  feet  in  diameter, 

n  =  2. id; 

and  for  wheels  25  to  40  feet  in  diameter, 

n  =  2.$d. 

The  depth  of  shrouding  for  these  wheels  is  about  12  inches, 
and  the  bucket  opening  is  about  J  of  a  square  foot  for  each  cubic 
foot  of  bucket  contents,  or  is  about  7  inches  in  width. 

Overshot  water-wheels  may  be  employed  to  operate  through 
gearing  or  belting  any  of  the  usual  forms  of  reciprocating  or 
centrifugal  pumps,  and  will  elevate  volumes  of  water  to  heights 
proportioned  to  the  power  they  are  capable  of  developing. 

c.  Turbine  Water-wheels.— Turbine  wheels  may  be  divided 
into  two  classes,  according  as  they  are  acted  on  (i)  through 
pressure  and  (2)  through  reaction.  Pressure  wheels  have  curved 
float-boards  along  which  the  water  glides.  Reaction  wheels 
consist  of  an  arrangement  of  pipes  from  which  water  issues 
tangentially.  To  this  latter  class  really  belong  Pelton  wheels, 
which  are  vertical  reaction  wheels. 

While  pressure  and  reaction  wheels  are  similar  in  con- 
struction, they  differ  in  that  in  the  former  the  passages  between 
the  vanes  are  not  completely  filled  with  water,  while  in  reaction 
wheels  the  water  fills  and  flows  through  the  whole  section  of 


WATER-WHEELS  83 

the  discharge-pipe.  Turbines  are  again  distinguished  as  (i) 
outward-,  (2)  inward-,  and  (3)  mixed-  or  parallel-flow  turbines. 
The  former  receive  the  water  at  the  center  and  deliver  it  at  the 
periphery  of  the  revolving  wheel,  the  regulating  apparatus 
consisting  of  a  ring  inserted  between  the  outer  periphery  of  the 
guide-blades  and  the  internal  periphery  of  the  revolving  wheel. 
In  inward-flow  turbines  the  motion  of  the  water,  as  the  name 
implies,  is  practically  the  reverse  of  that  for  outward  flow. 
Turbines  possess  an  advantage  over  vertical  water-wheels  in 
that  they  may  be  used  with  any  fall  of  water  from  i  foot  to 
several  hundred  feet.  The  chief  differences  between  turbines 
and  vertical  water-wheels  are  that  the  turbines  may  be  drowned, 
but  vertical  wheels  must  be  elevated  above  the  water  in  the  tail- 
race;  the  turbine  takes  its  supply  at  the  bottom  of  the  fall 
and  the  water-wheel  at  the  top  or  beginning  of  the  fall,  and 
therefore  the  former  obtains  nearly  the  whole  pressure  due  to 
the  head  or  height  of  the  fall;  turbines  work  without  material 
loss  of  energy  when  drowned  and  move  with  a  greater  velocity 
than  vertical  water-wheels,  and  hence  may  be  reduced  in  size 
and  weight  for  equal  power. 

Mixed-  and  parallel-flow  turbines  may  be  fixed  at  any 
convenient  distance  above  the  tail-race,  and  must  have  suffi- 
cient water  above  the  guide-blades  to  allow  it  to  enter  freely 
without  eddies. 

Of  the  American  makes  of  water-wheels  probably  the  two 
most  extensively  employed  are  the  Victor  turbine  and  the 
Leffel  turbine,  though  a  number  of  other  types  are  manufactured. 
These  wheels  have  been  extensively  employed  for  all  the  various 
purposes  to  which  power  may  be  applied,  and  a  number  of 
pumping  plants  for  irrigation  operated  by  such  turbines  have 
been  erected  in  the  West.  These  turbines  come  in  sizes  and 
powers  ranging  from  a  few  inches  in  diameter  under  a  head  of 
but  a  few  feet,  and  capable  of  developing  as  little  as  one  horse- 
power, up  to  the  enormous  sixes  which  have  recently  been 
built  which  are  capable  of  developing  as  much  as  20,000  horse- 
power, and  which  may  be  operated  under  several  hundred 
feet  of  head. 


84  PUMPING  FOR  IRRIGATION 

d.  Pelton  Water-wheels. — Pelton  water-wheels  are  simple 
in  construction  and  not  liable  to  be  clogged  or  to  get  out  of 
order,  and  can  be  worked  under  great  heights  of  fall.  They 
are  vertical,  tangential  reaction  wheels,  and  powrer  is  derived 
from  the  impulse  of  the  head  of  water  supplied  by  a  pipe  which 
discharges  upon  the  wheel-buckets  on  the  lower  side  of  the 
wheel  through  a  nozzle.  The  buckets  which  are  on  the  periphery 
of  a  Pelton  wheel  are  of  metal,  cup-shaped,  and  divided  into 
two  compartments  in  such  way  as  to  develop  the  full  force  of 
the  impinging  stream,  while  in  passing  out  the  water  sweeps  the 
curved  sides  with  a  reactionary  influence,  giving  it  the  effect 
of  a  long  impact.  The  power  of  this  wheel  does  not  depend  upon 
its  diameter,  but  upon  the  volume  and  head  of  water  supplied. 
Pelton  wheels  are  not  recommended  for  heads  less  than  50  feet, 
as  below  this  head  turbines  are  usually  more  efficient.  But 
above  200  feet  head  and  up  to  2000  feet  a  Pelton  wheel  is  best, 
as  no  other  wheel  produces  like  efficiency  or  works  with  equal 
simplicity.  These  wheels  are  adapted  to  a  wide  range  of  con- 
ditions of  water-supply,  producing  power  under  the  most  vary- 
ing conditions  with  efficiency.  This  is  accomplished  by  simple 
change  of  nozzle-tips,  by  varying  the  size  of  stream  thrown 
upon  the  wheel,  or  by  shutting  off  one  or  more  of  the  multiple 
nozzles,  the  power  of  which  may  thus  be  varied  from  maximum 
to  25  per  cent  without  appreciable  loss.  The  buckets  being 
open,  there  is  no  uncertainty  or  annoyance  from  derangement 
of  the  parts,  or  stoppage  by  driftwrood  or  other  substances  in 
the  water.  They  are  relatively  cheap  of  installment,  and  may 
utilize  the  water  from  a  small  spring  or  creek  as  well  as  from 
the  largest  source  of  supply.  These  wheels  admit,  by  varying 
their  diameter,  of  being  placed  directly  on  the  crank-shaft 
of  power  pumps  without  intermediate  gearing  or  connections. 

4.  Internal  Combustion  Engines. — The  development  of  the 
gas  and  vapor  engines  actuated  by  internal  explosions  are  not 
only  relatively  economical  of  fuel,  but  are  adaptable  to  small 
units,  and  are  so  nearly  automatic  as  to  require  only  occasional 
visits  to  keep  them  running  properly,  and  when  out  of  order 
merely  stop  until  the  difficulty  is  remedied.  These  important 


HOT-AIR  AND  ALCOHOL  PUM PING-ENGINES  85 

advantages  have  given  them  a  prominent  place  in  the  field  of 
individual  pumping  plants.  Their  most  important  handicap 
is  the  high  grade  of  fuel  required,  generally  either  gasoline,  or 
other  volatile  oils  called  distillate.  A  greater  economy  in  the 
fuel  used  by  such  engines  is  sometimes  obtained  by  producing 
the  gas  consumed  from  oil  or  coal  in  the  plant  itself.  The  lignite 
outcropping  abundantly  in  some  regions  is  well  adapted  to  this 
use. 

5.  Hot-air,  Gasoline,  and  Alcohol  Pumping-engines. — Hot- 
air  pumping-engines  depend  for  their  operation  on  power 
developed  by  the  expansion  of  heated  air  without  the  interposi- 
tion of  steam  or  other  agency  to  convert  the  heat  into  motion. 
Alcohol  and  gasoline-engines  are  likewise  operated  without 
converting  the  heat  produced  by  combustion  into  steam,  but 
depend  upon  the  expansive  force  produced  by  the  explosion  of 
alcohol  or  gasoline  converted  into  gas  when  brought  into  contact 
with  air.  They  have,  under  certain  conditions,  decided  advan- 
tages over  water-  and  steam  motors  in  that  they  can  be  employed 
where  there  is  not  a  sufficient  water-supply  to  operate  a  water- 
motor,  utilizing,  as  they  do,  practically  no  water,  and  therefore 
being  able  to  pump  all  that  is  available  for  irrigation.  They 
may  be  employed  where  steam-pumps  cannot  be,  both  because 
of  their  economy  in  water  consumption  and  because  of  the  kinds 
of  fuel  which  they  may  use;  gasoline  and  alcohol  being  service- 
able in  arid  regions  where  transportation  of  fuel  is  expensive 
and  hot-air  engines  being  capable  of  utilizing  any  variety  of  fuel. 
They  are  compact,  and  simple  of  erection  by  comparatively 
unskilled  machinists,  and  can  be  operated  at  the  least  expense 
for  supervision.  Denatured  alcohol  is  efficient  fuel  when 
utilized  in  a  specially  designed  alcohol  engine,  of  which  there  are 
several  successful  makes  on  the  market.  Such  alcohol  can  be 
made  on  the  farm  from  waste  or  refuse  vegetables,  fruit,  or 
grain. 

Hot-air  engines  are  constructed  almost  wholly  as  pumping- 
engines,  and  the  motive  power  and  pumping  apparatus  are 
combined  in  one  machine  inseparably  connected.  Many  thou- 
sands of  these  machines  are  in  use,  chiefly  for  pumping  small 


86  PUMPING  FOR   IRRIGATION 

quantities  of  water  in  cities  for  manufacturing  or  domestic 
uses,  only  a  few  being  employed  in  pumping  water  for  irrigation. 
They  are  simple  of  construction  and  there  is  no  possibility  of 
explosion,  as  may  occur  through  carelessness  with  a  gasoline- 
engine.  When  once  started  they  require  no  further  attention 
than  the  replenishment  of  fuel. 

Gasoline-  and  alcohol-engines  are  used  extensively  in  some 
portions  of  the  West,  notably  in  Kansas,  for  pumping  water  for 
irrigation.  They  are  made  of  various  dimensions,  pumping  a 
corresponding  volume  of  water,  and  they  are  constructed  as 
combined  motive  and  pumping  plants  or  as  separate  motors  to  be 
attached  to  various  forms  of  pumps.  The  chief  advantages 
which  these  machines  have  are  their  compactness  and  simplicity 
of  installation  and  operation,  and  their  cheapness. 

6.  Steam  Power. — Some  of  the  largest  irrigation  pumping 
plants  in  existence  in  point  of  power  developed  and  water  pumped 
are  actuated  by  steam  power.     In  the  Hawaiian  Islands  large 
steam  pumps  are  employed  to  lift  water  as  much  as  550  feet  for 
the  irrigation  of  sugar  cane.     The  crop  must  be  very  valuable  to 
justify   any   such   lift.     Very  large   steam  plants   for  low  lifts 
and  large  quantities  of  water  are  employed  upon  the  rice  planta- 
tions   of    Louisiana.     The    large    plants    have    employed    the 
reciprocating  engine  and  pump  direct-connected,  or  steam  pump. 
For  some  cases  a  higher  efficiency  may  be  obtained  by  the  use 
of  steam  turbines  which  are  especially,  on  account  of  their  high 
speed,  adaptable  to  the  actuation  of  electric  generators,  which 
in  turn  may  furnish  current  to  a  number  of  pumps  installed  at 
different  localities.     Where  the  water  is  to  be  obtained  from 
numerous  wells,  this  method  of  distribution  is  especially  advan- 
tageous.    A  steam  plant  to  be  economical  must  be  large,  as  it 
requires  continuous  attendance  and  must  have  elaborate  pro- 
visions for  economy  of  fuel.     The  investment  in  such  a  plant  and 
the  area  irrigated  are  usually  beyond  the  means  of  the  individual 
irrigator,  and  most  successful  plants  of  this  character  are  handled 
by  large  corporations  or  municipalities. 

7.  Pumps. — Although  other  types  are  used,  the  centrifugal 
pump  dominates  the  irrigation  field. 


PUMPS 


87 


Centrifugal  pumps  lift  water  by  means  of  a  disk  bearing 
curved  blades  which  revolves  rapidly  within  a  chamber,  which 
fits  as  closely  as  possible  to  leave  clearance  for  rapid  motion. 
The  blades  force  the  water  through  the  delivery  pipe.  They 
are  sometimes  submerged  in  the  water  to  be  pumped,  or  may  be 
placed  a  few  feet  above  the  water,  in  which  case  they  require 
priming  to  start  them.  Centrifugal  pumps  are  of  several  varie- 
ties, differing  in  form  or  detail,  but  acting  on  the  same  principle. 

The  centrifugal  type  of  pump  is  the  favorite  where  large 
volumes  of  water  must  be  lifted  through  a  moderate  elevation. 
Its  main  advantages  are  simplicity,  reliability,  low  cost,  and 
freedom  from  serious  trouble  with  silt,  leaves,  etc.  When 
properly  designed  for  the  conditions  under  which  it  is  to  operate 
it  shows  efficiencies  above  80  per  cent  for  heads  between  30  to 
60  feet,  with  somewhat  less  outside  those  limits.  The  loss 
at  entrance  of  suction  pipe  is  over  90  per  cent  of  the  velocity 
head  at  entrance,  and  at  the  exit  of  the  discharge  pipe  the  loss 
is  the  entire  velocity  head.  These  losses  can  be  greatly  dimin- 
ished by  tapering  the  pipe  to  larger  section  in  both  directions 
from  the  pump.  To  be  fully  effective,  however,  the  taper 
must  be  very  gradual,  especially  at  the  discharge  end. 

Prof.  W.  B.  Gregory  gives  the  following  table  as  an  illustra- 
tion of  the  advantage  of  expanding  the  suction  and  discharge 
pipes  in  directions  away  from  the  pump.  It  also  illustrates  the 
fact  that  this  is  more  important  at  the  discharge  than  at  the 
suction  side: 

TABLE   XVII.— CENTRIFUGAL  PUMP,    5   FEET  LIFT 


Form  of  Pipe 

Loss  of 
Head  at 
Entrance 

Loss  of 
Head  at 
Discharge 

Friction 
Loss, 
Straight 
Pipe 

Total 
Head 

GAIN 

Feet 

Per  cent 

Straight  2  ft.  diameter  . 

1.44 

i-55 

o.  24 

8.23 

0 

O 

Expanded  to  2  ft.  6  in. 

0-59 

0.63 

o.  24 

6.46 

1.77 

21-5 

Expanded  to  3  ft  

0.28 

0.31 

0.24 

5.83 

2.40 

29.1 

Expanded  to  4  ft  

O.OQ 

0.  10 

0.24 

5-43 

2.8o 

34-0 

The  screw  pump  pushes  the  water  along  by  means  of  an 
inclined  plane  in  the  form  of  the  threads  of  a  rapidly  revolving 


88 


PUMPING  FOR  IRRIGATION 


jgjjflggj^j£j| 
KXEMBB 

FIG.  17.— Windmill  and  Reservoir  near  Garden  City,  Kansas. 


FIG.  18.— Battery  of  Hydraulic  Rams,  Yakima  Valley,  Washington. 


PUMPS 


89 


FIG.  19.— Undershot  Water-wheel. 


FIG.  20. — Current  Wheel  or  Nona,  Lifting  Water  from  Salmon  River  for 

Irrigation. 


90  PUMPING  FOR  IRRIGATION 

screw,  working  inside  a  pipe.  It  is  especially  adapted  to  low 
heads,  as  it  does  not  require  the  water  to  move  with  as  high  a 
velocity  as  the  centrifugal  pump  requires,  and  may  achieve 
efficiencies  of  70  per  cent  for  heads  as  low  as  6  or  8  feet. 

Another  type  of  pump  advantageous  for  low  heads  is  the 
scoop  wheel,  a  view  of  which  is  shown  in  Fig.  22.  It  is  an  adapta- 
tion of  the  old-fashioned  paddle  wheel  used  on  river  steamers.  The 
paddles  push  the  water  up  a  curved  trough  fitting  them  closely 
without  touching.  It  moves  the  water  so  gently  that  its  efficiency 
is  almost  independent  of  the  lift,  but  it  cannot  be  well  adapted 
to  high  lifts.  Efficiencies  of  over  60  per  cent  are  attainable. 

8.  Direct  Pumping. — It  often  happens  that  the  location  of 
a  canal  on  the  adopted  grade  reaches  a  point  where  it  encounters 
topography  so  rough  that  economy  requires  it  to  be  dropped 
to  a  lower  level,  and  there  may  also  be  irrigable  land  at  higher 
level,  near  by,  which  it  is  desirable  to  reach.  In  such  a  case 
it  may  be  possible  to  utilize  the  power  generated  by  the  falling 
water  at  the  drop,  to  raise  a  portion  of  it  to  a  higher  level. 
Where  this  is  done  at  the  same  point  with  one  installation  of 
machinery,  this  is  called  a  direct-pumping  plant.  Several  such 
plants  have  been  installed  by  the  United  States  Reclamation 
Service,  a  typical  one  being  that  on  the  Huntley  Project,  Mon- 
tana, where  the  main  canal  carries  200  second- feet  of  water, 
which  descends  a  vertical  distance  of  34  feet,  through  a  pressure 
pipe  into  a  casing  enclosing  a  centrifugal  pump  mounted  on  a 
vertical  shaft  above  a  turbine  water-wheel  on  the  same  shaft. 
One  hundred  and  fifty  second-feet  of  the  water  passes  through 
the  turbine  into  the  canal  below,  thus  turning  the  shaft  and 
actuating  the  centrifugal  pump  which  lifts  50  second-feet  of 
the  water  to  a  level  45  feet  above  that  of  the  main  canal.  This 
machine  was  built  under  a  requirement  of  51  per  cent  efficiency 
and  approximates  this  in  practice. 

It  is  seldom  that  the  velocity  of  highest  efficiency  is  the 
same  for  both  water-wheel  and  pump,  and  hence  it  sometimes 
occurs  that  higher  efficiency  can  be  obtained  by  a  separate 
installation  of  these  two  machines,  connecting  them  by  gearing 
or  belting  to  secure  the  best  velocity  in  each. 


HYDRAULIC  RAM  91 

9.  Hydraulic  Ram. — The  commonest  form  of  direct  pumping 
plant  is  the  hydraulic  ram.  This  uses  a  large  volume  of  water 
falling  a  moderate  distance,  to  pump  a  smaller  quantity  of  water 
through  a  greater  head.  In  this  device,  a  pipe  (A)  leads  from 
the  source  of  supply  to  a  valve  box  (B)  and  sends  a  branch  to  an 
air  chamber  (C),  from  which  the  delivery  pipe  (D)  leads  to  the 
higher  level.  The  valve  in  the  valve  box  opens  downward, 
and  is  made  heavy  enough  to  remain  open  with  a  moderate 
flow  of  water  but  closes  suddenly  when  the  velocity  of  the  escap- 
ing water  reaches  a  certain  point.  When  the  valve  closes  the 
rushing  water  is  suddenly  checked,  producing  a  water  hammer 
which  opens  the  valve  into  the  air  chamber  and  compresses 


FIG.  21. — Diagram   Illustrating   Principle  of  Hydraulic   Ram. 

the  air,  and  is  relieved  in  part  by  flowing  into  the  delivery  pipe. 
When  the  pressure  equalizes,  the  air  chamber  valve  closes, 
and  the  flow  through  the  delivery  pipe  is  continued  for  a  brief 
period,  by  the  expansion  of  the  compressed  air  in  the  air  chamber. 
As  the  air  in  this  chamber  is  gradually  absorbed  and  carried 
out  by  the  water,  provision  must  be  made  for  its  renewal,  or  the 
efficiency  of  the  ram  will  decrease.  When  the  water  in  the 
supply  pipe  is  quiet,  the  valve  in  the  valve  box  (B)  falls,  the 
flow  of  water  begins  again,  and  the  process  is  repeated. 

Thus,  the  flow  from  a  hydraulic  ram  is  a  series  of  pulsations, 
and  each  impulse  has  to  overcome  the  inertia  of  the  column 
of  water  in  the  delivery  pipe.  If  two  such  rams  are  connected 
with  the  same  discharge  pipe,  and  their  pulsations  do  not  coin- 
cide, the  discharge  is  more  nearly  continuous,  and  less  energy 


92 


PUMPING  FOR  IRRIGATION 


is  wasted;  and  this  becomes  still  more  the  case,  as  the  number 
of  rams  is  increased.  An  installation  of  eleven  hydraulic  rams 
in  the  Yakima  Valley  gave  an  efficiency  of  over  71  per  cent 
when  quite  old,  while  a  single  ram  will  seldom  give  better  than 
50  to  60  per  cent  efficiency.  Like  other  mechanical  appliances, 
however,  the  hydraulic  ram  is  susceptible  of  great  ranges  in 
efficiency,  and  a  battery  of  two  1 2-inch  rams  installed  at  Seattle, 
are  reported  by  Carver  to  have  shown  efficiencies  as  follows : 

TABLE  XVIII.— TESTS   OF    12-INCH  HYDRAULIC   RAM, 
SEATTLE,   WASH. 


Strokes 

Power 
Head 

Pumping 
Head 

Water 

Wasted 

Water 
Pumped 

Efficiency 
Per  cent 

per 

Ft. 

Ft. 

c.  f.  s. 

c.  £.  s. 

q(h) 

H 

h 

0 

q 

(Q+q)H 

65 

48.7 

130.7 

1.  08 

0-555 

90.8 

50 

48.0 

131.6 

i-53 

0-755 

90-5 

45 

48.0 

133-8 

1.78 

0.846 

89.6 

41 

47-9 

131.2 

1.91 

0.915 

88.8 

40 

47-9 

133-8 

2.04 

0.930 

87.5 

37 

47-9 

127.8 

2.04 

I  .020 

89.0 

•       32 

47.8 

135-9 

2.66 

1.  080 

82.3 

i 

10.  Air-lift   Pumping. — Water   is   sometimes   pumped   from 
wells  by  means  of  compressed  air,  by  forcing  the  air  through  a 
pipe  to  the  bottom  of  the  well  casing  and  there  releasing  it. 
This  method  can  be  used  only  for  vertical  lifts  from  wells  of 
considerable  depths.     It  is  not  applicable  to  lifts  of  more  than 
200  feet,  unless  the  lifts  are  arranged  in  series. 

The  area  of  the  air  pipe  should  be  between  15  per  cent  and 
20  per  cent  of  that  of  the  water'  pipe,  and  from  one-half  to 
two- thirds  of  the  air  pipe  should  be  submerged.  Under  favor- 
able conditions  an  efficiency  of  about  30  per  cent  is  attained, 
although  results  in  practice  are  usually  lower,  and  laboratory 
tests  may  be  higher.  The  system  is  well  adapted  to  sandy 
water,  as  there  is  no  machinery  or  valves  to  wear.  It  is  little 
used  on  account  of  low  efficiency. 

11.  Hydro-electric  Pumping. — Where  the  pumping  is  to  be 
performed  at  a  distance  from  the  drop  where  power  can  be 


AIR  LIFT-PUMPING  93 

generated,  electric  power  may  be  generated  at  the  drop,  and 
transmitted  over  wires  to  one  or  several  points  where  pumping 
is  required.  Such  pumping  may  be  from  canals,  or  from  wells 
drawing  upon  the  ground  water,  and  opportunities  for  their 
installation  are  very  numerous  in  irrigated  regions,  and  in  fact 
occur  on  nearly  every  large  irrigation  system. 

The  largest  existing  hydro-electric  installation  for  irrigation 
pumping  is  at  the  Minidoka  dam  on  the  irrigation  project  of 
the  same  name  built  and  operated  by  the  United  States  govern- 
ment. 

At  this  point,  a  dam  was  built  in  Snake  River  to  raise  the 
water  into  canals  on  each  side  of  the  river,  38  feet  above  the 
bed  of  the  river.  The  main  dam  is  of  loose  rock  faced  with  gravel 
and  earth,  and  its  south  abutment  at  the  river  bank  merges  into 
a  concrete  weir  built  on  the  lava  bench,  which  serves  as  a  spill- 
way, about  3000  feet  long.  The  weir  is  surmounted  by  a  series 
of  buttresses  against  which  are  placed  flash  boards  to  serve  as  a 
movable  crest  to  store  flood  waters  for  irrigation.  The  available 
storage  capacity  above  the  level  necessary  for  diversion  pur- 
poses is  about  54,000  acre-feet.  Below  this  dam  about  300,000 
acres  of  land  are  irrigated,  the  water  for  which  must  pass  the 
dam  and  is  available  for  the  development  of  power  under  such 
head  as  the  dam  affords,  which  is  about  46  feet  on  an  average. 

The  present  development  consists  of  five  2ooo-horse-power 
vertical  turbines,  direct  connected  to  1500  k.v.a.  alternators, 
generating  3-phase  6o-cycle  current  at  2300  volts.  The  turbines 
operate  under  a  normal  gross  head  of  46  feet  at  a  speed  of  200 
r.p.m. 

The  current  from  the  alternators  is  transformed  from  2300 
volts  to  33,000  volts,  by  five  transformers  of  1500  k.v.a.  capacity 
each.  This  current  is  transmitted  over  duplicate  copper  trans- 
mission lines,  a  distance  of  n  miles  by  the  shortest  line  to  the 
nearest  pumping  station. 

At  the  lower  end  of  the  south  side  gravity  canal  is  located  the 
first  pumping  plant,  which  consists  of  four  centrifugal  pumps 
with  capacity  of  160  second-feet  each,  and  one  pump  of  75 
second-feet  capacity,  or  a  total  capacity  of  715  second-feet. 


94 


PUMPING  FOR  IRRIGATION 


The  lift  is  31  feet  net,  and  at  this  level  a  canal  carries  water  to 
cover  about  10,000  acres.  Another  canal  runs  in  cut  to  a  suitable 
location  for  the  second  pumping  station  which  is  equipped  with 
four  pumps  of  i6o-second-feet  capacity  each,  which  lift  the  water 
31  feet  higher,  from  which  level  about  15,000  acres  are  irrigated, 
and  the  balance  of  the  water  is  carried  to  the  third  pumping 
station,  which  has  two  pumps  of  i6o-second-feet  capacity  each 
and  one  of  75-second-feet  capacity,  and  supplies  about  23,000 
acres  of  land.  The  lift  at  each  station  is  about  31  feet  and 


FIG. 


22. — Scoop  Wheel,  Lifting  Water  3!  feet,  60  per  cent  Efficient. 


the  average  lift  is  about  64  feet.  All  the  pumps  are  of  the 
vertical  shaft  type  submerged,  with  both  top  and  bottom  suction, 
located  in  separate  concrete  chambers,  16  by  17  feet,  protected 
by  steel  trash  racks.  The  larger  pumps  have  impellers  of  44 
inches  diameter  and  discharges  48  inches  diameter,  giving  a 
discharge  velocity  of  10.4  feet  at  rated  capacity,  and  a  speed  of 
300  r.p.m.  The  casing  of  the  pump  is  of  cast  iron,  and  the 
impellers  are  of  steel  plate  with  cast-iron  shroud  rings.  The 
discharge  pipes  gradually  enlarge  to  66  inches  diameter  and  are 


THE  HUMPHREY  DIRECT-EXPLOSION  PUMP 


95 


merged  into  reinforced-concrete  pipe,  reaching  to  the  top  of  the 
lift,  where  it  is  equipped  with  a  steel  flap  valve  which  remains 
open  while  the  pump  is  operating,  and  closes  when  it  stops. 
The  motive  power  for  the  pumping  unit  is  furnished  by  a  600- 
horse-power  3-phase  synchronous  motor,  wound  for  2200  volts, 
to  which  pressure  the  current  is  transformed  from  the  trans- 
mission voltage  of  about  30,000.  All  the  pumping  stations  are 
housed  in  buildings  of  reinforced  concrete. 

The  electric  current  is  also  transmitted  to  numerous  small 
pumping  stations  where  it  is  necessary  to  lift  water  from  3  to  5 
feet  to  cover  a  few  hundred  acres.  This  is  accomplished  by 
steel  scoop  wheels  with  an  efficiency  of  about  60  per  cent. 

12.  The  Humphrey   direct-explosion  pump  is  used  at  Del 


Pumping  Station 


FIG.   23. — Direct  explosion  Pumping  Plant  to  Raise  Irrigating  Water. 

Rio,  Texas,  to  pump  about  60  cubic  feet  per  second  to  a  height 
of  37  feet  from  the  Rio  Grande.  This  type  of  pump  has  few 
moving  parts  and  combines  the  prime  motor  and  pump  in  one 
structure,  consisting  mainly  of  a  simple  system  of  pipes,  valves, 
and  tanks,  as  shown  in  Fig.  23,  using  gas  produced  at  the  site. 
To  start  the  pump,  the  proper  mixture  of  air  and  gas  is  forced 
into  a  cylinder  by  a  small  air  compressor  of  the  two-cylinder 
type,  one  cylinder  pumping  air  and  the  other  pumping  gas. 

After  the  proper  mixture  of  air  and  gas  is  forced  into  the 
cylinder  by  the  compressor,  the  charge  is  fired  by  an  electric 
spark,  all  the  valves  being  shut  at  the  instant  when  the  explosion 


96  PUMPING  FOR  IRRIGATION 

occurs.  The  charge  of  gas  and  air  is  exploded  directly  over 
the  surface  of  the  water,  no  piston  or  moving  parts  being  used. 
The  increase  in  pressure  resulting  from  the  explosion,  all  valves 
being  closed,  drives  the  water  in  the  pump-head  downwards 
and  sets  the  whole  column  of  water  in  the  play  pipe  in  motion. 
This  column  of  water  attains  kinetic  energy  during  the  period 
when  work  is  being  done  upon  it  by  the  expanding  gases.  By 
the  time  the  gases  resulting  from  the  explosion  have  expanded 
to  atmospheric  pressure  the  water  in  the  play  pipe  is  moving 
at  a  very  high  velocity.  As  the  motion  of  this  column  of  water 
cannot  be  suddenly  arrested  the  pressure  in  the  explosion 
chamber  falls  below  atmospheric  pressure.  When  this  occurs, 
a  quantity  of  water  enters  through  the  suction  valves,  most  of 
which  follows  the  moving  column  in  the  play  pipe  and  the  rest 
rises  in  the  explosion  chamber. 

As  soon  as  the  column  of  water  in  the  play  pipe  comes  to 
rest,  it  starts  to  move  back  towards  the  pump  and  gains  in 
velocity  until  the  water  reaches  the  level  of  the  exhaust  valves 
which  are  shut  by  impact.  A  certain  quantity  of  the  burned 
products  mixed  with  the  scavenging  air  is  now  imprisoned  in  the 
cushioned  space  and  the  kinetic  energy  of  the  moving  column 
is  expended  in  compressing  this  gas  cushion  to  a  very  much 
greater  pressure  than  due  to  the  static  pumping  head.  As  a 
result  of  the  energy  stored  up  in  the  entrapped  compressed  gases, 
the  column  of  water  is  again  forced  outward.  The  pressure 
in  the  gas  head  is  again  reduced  to  atmospheric  pressure  and 
below,  at  which  a  fresh  charge  of  gas  and  air  is  drawn  in  to 
the  explosion  chamber.  Again  the  column  of  water  returns 
under  the  pressure  in  the  play  pipe,  compresses  the  charge  of  gas 
and  air  which  is  then  ignited  to  start  a  fresh  cycle  of  operation. 

The  period  of  cycle  of  the  pump  is  determined  primarily  by 
the  length  of  the  reciprocating  column  of  water  in  the  play  pipe. 
As  a  general  rule,  assuming  the  column  to  be  of  a  uniform  section, 
the  period  of  vibration  is  almost  proportional  to  the  square  root 
of  the  length  of  the  water  column.  The  Del  Rio  pump  will 
average  about  twelve  complete  cycles  per  minute. 

The  thermal  efficiency  of  the  pump  is  guaranteed  to  be  not 


RICE  IRRIGATION 


97 


less  than  20  per  cent.  English  pumps  of  this  type  have  reached 
a  thermal  efficiency  of  over  22  per  cent. 

13.  Rice  Irrigation. — The  irrigation  of  rice  in  Louisiana  is 
an  important  industry,  and  this  has  become  one  of  the  staple 
crops  of  the  state.  It  was  formerly  customary  to  place  flumes 
in  the  levees  of  the  Mississippi  River  to  admit  water  to  the  rice 
fields,  but  the  menace  to  the  safety  of  the  levees  led  to  the 
prohibition  of  this  practice,  and  thereafter  siphons  have  been 
used  to  lift  the  water  over  the  leeves.  At  low  water  it  is  generally 
necessary  to  pump  the  water  from  the  river  to  supply  the  siphons. 

Large  quantities  of  rice  are  also  produced  on  the  uplands,  to 
which  water  is  pumped  to  various  heights,  sometimes  more  than 
50  feet.  The  quantity  of  irrigation  water  applied  in  a  season 
varies  with  the  season  and  the  soil,  from  i  to  3  feet  in  depth, 
averaging  about  2\  feet. 

TABLE  XIX.— PRODUCTION  OF  RICE,   1917,  IN  UNITED  STATES 


Yield 

Production, 

VALUE  AT 

FARM 

Acreage 

per  Acre, 
Bushels 

Bushels 

Total 

Per  Acre 

North  Carolina  
South  Carolina. 

300 
3OOO 

26.0 
2  c    o 

7,800 
"if  OOO 

$16,000 
146  ooo 

$50.70 
4.8    7C 

Georgia    . 

QOO 

30  o 

27,000 

C7  OOO 

c8  ico 

Florida  

800 

26  .O 

20,800 

41,000 

^o  70 

Missouri  .... 

4OO 

4.5    o 

18,000 

34,000 

85  50 

Alabama  
Mississippi  .... 

400 
2,IOO 

27.0 

30  o 

10,800 
63,000 

23,000 

120,000 

5i-3o 

57    OO 

Louisiana  
Texas.  . 

5OO,OOO 
23O,OOO 

36.5 
27  .O 

18,250,000 
6,210,000 

34,675,000 

12,420,000 

69-35 
54.OO 

Arkansas  

I46,2OO 

4I.O 

5,994,000 

11,389,000 

77.9O 

California  .  .  . 

8o,OOO 

7O.  O 

5,600,000 

9,800,000 

I  2  2  .  50 

United  States  

964,100 

37-6 

36,276,400 

$68,717,000 

$71.28 

The  use  of  the  centrifugal  pump  is  nearly  universal  on  the 
rice  plantations  for  small  installations  designed  for  more  than  10 
feet  lift.  The  water  is  pumped  from  streams  where  these  are 
available,  but  a  great  many  take  water  from  wells,  from  15  to  50 
feet  in  depth.  More  than  2000  wells  are  thus  used  for  the 


98  PUMPING  FOR  IRRIGATION 

irrigation  of  rice  in  Louisiana  and  Texas,  the  motive  power  being 
usually  steam  in  Louisiana,  while  gasoline  is  frequently  employed 
in  Texas.  These  two  States  produce  over  three-quarters  of  the 
rice  produced  in  the  United  States,  most  of  the  rest  being  grown 
in  Arkansas  and  California.  Over  90  per  cent  of  this  is  irrigated 
by  pumping,  and  this  mainly  by  centrifugal  pumps. 

According  to  Gregory,  the  largest  irrigation  pumping  plant 
in  the  rice  country  is  that  of  the  Neches  Canal  near  Beaumont, 
Texas,  which  has  a  capacity  of  about  440  cubic  feet  per  second, 
pumping  against  a  head  of  30  to  35  feet.  This  is  accomplished 
by  six  rotary  chamber  wheel  pumps.  These  pumps  have  shown 
good  efficiency  and  reliability,  but  some  plants  of  this  type 
have  given  considerable  trouble.  One  complication  is  the  irregu- 
lar discharge  velocity,  making  it  necessary  to  provide  air 
chambers  near  the  pump.  This  and  other  characteristics  require 
a  higher  grade  of  skill  in  their  operation  and  maintenance  than 
is  necessary  for  the  centrifugal  pump. 

REFERENCES  FOR  CHAPTER  VII 

MURPHY,  E.  C.     The  Windmill,  Its  Efficiency  and  Economic  Use.     W.  S.  P. 

41  and  42 1  U.  S.  Geological  Survey. 
GREGORY,  W.  B.     Evolution  of  Low-lift  Pumping  Plants  in  Gulf  Coast  Country. 

American  Soc.  Mechanical  Engineers,  New  York. 
DAVIS,  A.  P.     Irrigation  Works  Constructed  by  United  States.     John  Wiley  & 

Sons,  New  York. 
ETCHEVERRY,  B.  A.     Use  of  Irrigation  Water.     McGraw-Hill  Book  Company, 

New  York. 
FLEMING,  B.  P.     Practical  Irrigation  and  Pumping.     John  Wiley  &  Sons,  New 

York. 
TAIT,  C.  E.     Use  of  Underground  Water  for  Irrigation,  at  Pomona,  Cal.     Bulletin 

No.  236,  U.  S.  Office  of  Experiment  Stations. 
MAHAN,  F.  A.     Water  Wheels.     E.  &  F.  Spon,  New  York. 
SCHLICHTER  &  WOLF.     Underflow  of  South  Platte   Valley.     W.  S.  P.  No.  184, 

U.  S.  Geological  Survey. 
NEWELL    &    MURPHY.     Principles    of    Irrigation    Engineering.     McGraw-Hill 

Book  Company,  New  York. 
O'SHAUGHNESSY,  M.  M.     Irrigation  Works  in  Hawaiian  Islands.     Engineering 

News,  April  15,  1909. 
WILSON,  HERBERT  M.     Pumping  Water  for  Irrigation.     W.  S.  P.  No.  i,  U.  S. 

Geological  Survey. 
HUMPHREY,  H.  A.     Direct-Acting  Explosion  Pump.     Engineering  News,  Dec.  2, 

1909. 


CHAPTER  VIII 
IRRIGABLE  LANDS 

ONE  of  the  first  and  most  important  fundamentals  to  deter- 
mine regarding  a  proposed  irrigation  project,  is  the  area  and 
character  of  the  irrigable  land.  Simple  as  this  may  seem,  it  is  a 
frequent  cause  of  failure  of  such  projects,  that  only  cursory 
attention  was  given  this  important  element  in  planning  the 
projects. 

i.  Topography. — For  successful  irrigation  the  land  should 
have  some  slope  in  order  that  the  water  may  be  induced  to  run 
over  it  in  gravity  canals  and  farm  ditches.  When  the  water 
in  a  canal  is  quiescent,  and  no  current  can  be  detected,  its  surface 
is  level,  or  practically  so,  and  in  order  to  induce  a  flow,  a  con- 
siderable slope  must  be  given  its  surface.  Sometimes  an  exten- 
sive plain,  perhaps  an  ancient  lake  bed,  is  so  flat  that  it  fur- 
nishes no  considerable  slope  in  any  direction  on  which  to  build 
a  canal  with  natural  slope  sufficient  to  carry  the  irrigation  water. 
This  water  must  therefore  be  provided  at  the  edge  of  the  plain 
at  sufficient  elevation  so  that  by  confining  it  between  dikes 
it  can  be  held  above  the  level  of  the  land  with  its  surface  gently 
sloping  in  the  direction  of  flow,  and  must  reach  each  field  to  be 
irrigated  with  the  water  surface  sufficiently  above  ground  so 
that  it  can  be  induced  to  run  over  the  fields  to  be  irrigated.  If 
the  distance  through  which  the  canal  must  be  thus  carried  is 
great,  the  height  of  the  dikes  forming  the  elevated  water  way 
may  be  too  expensive,  and  their  maintenance  too  precarious  to 
be  feasible.  In  general,  extensive  tracts  of  this  nature  are  not 
numerous,  and  when  small,  they  can  be  treated  as  above  indi- 
cated; but  owing  to  lack  of  grade  the  canals  must  have  small 

slope  and  low  velocity. 

99 


100 


IRRIGABLE  LANDS 


The  desirable  slope  of  the  irrigable  land  is  between  10  feet 
per  mile  and  30  feet  per  mile  in  the  direction  of  greatest  slope. 
Less  than  the  lower  limit  mentioned  involves  some  inconvenience 
in  getting  water  over  the  fields,  and  in  disposing  of  waste  water, 
while  more  than  30  feet  may  involve  extra  expense  in  providing 
drops  in  canals,  or  other  devices  to  avoid  destructive  velocities. 
A  typical  valley  usually  has  a  slope  parallel  with  its  drainage 


FIG.  24. — Shoshone  Desert  before  Irrigation. 

line  and  approximately  equal  thereto,  and  also  a  slope  from  the 
hills  normal  to  the  stream. 

While  the  above  limits  indicate  the  convenient  slopes,  the 
feasibility  of  irrigation  is  not  thus  limited  by  any  means.  Water 
can  be  successfully  applied  where  the  slope  is  little  or  nothing, 
and  also  on  side  hills  so  steep  that  plowing  and  other  farm 
operations  are  difficult;  but  such  conditions  require  special 
devices  and  expenditures,  and  great  care  in  the  application  of 


TOPOGRAPHY  101 

water.  In  countries  where  land  and  its  products  are  of  low 
value,  a  limit  of  slope  of  10  per  cent  is  sometimes  adopted,  and 
land  with  greater  slope  than  this  is  classed  as  non-irrigable. 
Where  land  values  are  higher,  however,  a  greater  slope  can  be 
tolerated  and  successfully  irrigated,  by  the  use  of  small  heads  of 
water  and  by  handling  it  with  care. 

While  the  ideal  plain  for  irrigation  is  a  smooth  gentle  slope, 
this  is  seldom  encountered  in  practice,  and  the  country  to  be 


FIG.  25.-  -Shoshone  Desert  after  Irrigation. 

irrigated  may  be  rolling  and  traversed  with  drainage  lines. 
If  these  are  very  large  or  frequent,  they  will  greatly  increase 
the  cost  of  the  system  by  the  necessity  of  providing  structures 
for  drainage  crossings.  If  the  natural  drainage  lines  are  not  too 
large  or  numerous,  they  may  be  advantageous  in  furnishing 
natural  escapes  for  storm  and  waste  waters. 

2.  Soil  Survey. — The  fertility  of  the  soil  must,  of  course, 
be  beyond  doubt.  In  any  country,  except  an  extremely  arid 
one,  the  fertility  of  the  soil  may  be  partly  inferred  from  the 


H)2  IRRIGABLE  LANDS 

character  of  the  natural  vegetation.  In  general  the  growth 
of  thrifty  sage  brush  is  an  excellent  indication,  as  this  does  not 
thrive  on  poor  soil  nor  on  that  impregnated  to  a  harmful  extent 
with  alkali.  In  some  cases,  however,  sage  brush  land  with  soil 
otherwise  excellent  may  be  dotted  with  frequent  spots  of  rock 
having  enough  soil  on  the  surface  and  in  crevices  and  pockets 
to  produce  a  fair  growth  of  sage  brush,  but  unfit  for  profitable 
cultivation.  Care  should  be  taken  to  ascertain  that  all  the 
land  classed  as  irrigable  has  at  least  2  or  3  feet  of  soil  over  any 
rock  or  hardpan  that  may  underlie  it. 

The  presence  of  greasewood  generally  denotes  that  for  some 
reason  the  conditions  are  not  favorable  for  sage  brush,  unless 
some  of  the. latter  also  occurs.  Frequently,  the  reason  is  a  heavy 
soil,  or  the  presence  of  alkali  in  too  great  an  amount  for  sage 
brush. 

The  freedom  of  the  passage  of  water  through  sand  is  fairly 
good  assurance  that  sandy  soil  contains  no  injurious  amounts 
of  alkali,  and  this  is  generally  true. 

Unless  the  character  of  vegetation  carried  by  a  tract,  or 
the  sandy  nature  of  the  soil  is  such  as  to  assure  the  absence 
of  harmful  amounts  of  alkaline  salts,  it  will  be  well  to  have  a 
soil  survey  made  to  determine  the  depth  and  character  of  the 
soil. 

Soil  samples  at  varying  depths  may  best  be  obtained  by 
means  of  a  soil  auger,  which  can  be  made  by  any  blacksmith. 
It  should  be  about  2  inches  in  diameter,  and  should  have  a  shaft 
that  can  be  extended  to  a  total  length  of  5  feet,  so  that  if 
desired  samples  at  that  depth  can  be  6btained.  The  samples 
obtained  should  be  kept  separate  and  carefully  labeled  as  to 
locality  and  depth  at  which  obtained.  All  samples  should  be 
tested  as  to  total  soluble  salts.  At  least  10  per  cent  of  the  samples 
taken  at  each  foot  of  depth  should  be  quantitatively  analyzed 
for  carbonate,  bicarbonate,  chloride  and  sulphate  of  sodium r 
and  sulphate  of  magnesium,  and  at  least  10  per  cent  of  the 
remaining  samples  should  be  subjected  to  simple  tests  to  show 
whether  the  indications  of  the  analyses  are  safe  guides,  and 
which  salt  predominates.  The  number  of  samples  taken  must 


SOIL  SURVEY  103 

depend  upon  the  degree  of  doubt  existing  as  to  the  quality  of 
the  soil,  and  should  be  determined  as  the  inquiry  progresses. 
If  the  results  are  fairly  uniform,  fewer  samples  are  necessary 
than  if  they  vary  greatly.  If  little  alkali  is  found,  fewer  samples 
are  necessary  than  if  the  alkali  is  so  abundant  as  to  stimulate 
doubt  of  the  arability  of  the  soil. 

Sandy  areas  are  sometimes  so  rough  as  to  be  expensive  in 
leveling.  There  is  often  a  tendency  for  the  sand  to  drift  about 
desert  shrubs,  and  if  the  dunes  or  hummocks  are  numerous 
they  may  occupy  too  much  room  to  permit  farming  between 
them,  and  the  cost  of  leveling  them  may  be  prohibitive.  Even 
land  that  to  the  casual  observer  appears  smooth  often  requires 
considerable  leveling  for  proper  irrigation.  Otherwise,  the 
water  applied  will  seek  the  low  places,  and  soak  them  too  heavily, 
while  the  high  points  are  left  dry.  Neglect  to  properly  level 
the  ground  is  one  of  the  commonest  failings  of  agriculture  under 
irrigation.  It  often  happens  that  depressions  or  sinks  occur 
which  in  their  natural  state  may  be  rather  more  fertile  than  the 
surrounding  land,  but  that  owing  to  lack  of  surface  drainage 
are  likely  under  irrigation  to  become  ponds  or  bogs,  too  wet  to 
cultivate.  It  may  be  possible  to  provide  drainage,  but  the  cost 
of  this  must  be  considered,  and  if  prohibitive  the  areas  must  be 
eliminated. 

All  areas  found  to  be  non-irrigable  or  of  doubtful  fertility 
must  be  liberally  measured  and  carefully  eliminated  from-  the 
irrigable  area,  and  the  extra  length  of  canals  and  laterals  neces- 
sary to  reach  a  given  area  must  be  liberally  allowed  for.  Allow- 
ance must  also  be  made  for  the  ground  to  be  occupied  by  roads, 
canals,  railroads,  drainage  lines,  and  any  other  areas  that  cannot 
be  actually  cultivated. 

Consideration  must  be  given  to  the  cost  of  clearing  the  land. 
If  heavily  timbered,  under  circumstances  in  which  the  timber 
cannot  be  marketed,  the  cost  of  clearing  plus  the  cost  of  irriga- 
tion may  nearly  equal  or  even  exceed  the  value  of  the  cleared 
land.  The  cost  of  clearing  smaller  brush  may  often  be  an 
important  element  in  considering  the  feasibility  of  the  pro- 
ject. 


104  IRRIGABLE  LANDS 

3.  Preparation  of  Land  for  Irrigation. — a.  Clearing. — In  the 
preparation  of  raw  land  for  irrigation,  the  first  step  is  the 
removal  from  the  surface  of  the  native  vegetation.  If  this  is 
simply  a  sod  of  grass,  rabbit  brush  or  other  small  vegetation, 
it  may  be  plowed  under,  by  means  of  a  strong  team  attached 
to  a  breaking  plow,  and  this  when  possible,  is  very  desirable, 
as  this  retains  the  vegetable  matter  in  the  soil  where  by  decay 
it  forms  valuable  plant  food,  generally  much  needed.  But  if  the 
ground  is  wholly  or  partially  covered  with  larger  shrubs  or  trees, 
these  must  be  removed  or  burned. 

Sagebrush  and  Greasewood. — The  commonest  grade  of  clearing 
required  is  sagebrush,  greasewood,  creosote  brush,  and  other 
shrubs  too  large  to  plow  under,  and  too  coarse  and  woody  to 
decay  readily.  In  many  cases  such  brush  is  worth  saving  for 
fuel,  or  for  riprapping  sandy  banks  to  prevent  erosion  by  wind 
or  water.  These  shrubs  cover  a  large  proportion  of  the  irrigable 
lands  in  the  Rocky  Mountain  and  Pacific  States,  and  usually 
range  from  3  to  6  feet  in  height.  They  may  be  easily  broken 
off  at  the  ground  surface  by  means  of  a  device  formed  of  three 
railroad  rails,  with  the  heads  interlocked,  and  firmly  bolted 
together,  leaving  the  flanges  projecting,  so  as  to  form  dull  edges. 
This  device  may  be  dragged  across  the  brush  by  eight  horses  and 
is  very  effective  in  breaking  down  the  brush,  which  may  then  be 
easily  collected,  and  either  burned  or  piled  for  future  use.  Sage- 
brush when  not  very  large  is  sometimes  plowed  out  by  heavy 
teams  or  traction  engines,  and  as  the  plowing  is  often  desirable, 
the  method  is  a  good  one,  although  more  expensive  than  the 
rail  method,  which  has  been  done  for  $2.50  to  $3.50  per  acre, 
while  the  plowing  method  costs  from  $1.00  to  $2.00  more.  The 
roots  of  these  shrubs  give  little  trouble  in  tillage,  and  soon  decay. 

Mesquite  is  an  abundant  native  of  the  Southwest,  is  larger 
and  tougher  than  sagebrush  and  has  much  heavier  stumps  and 
roots.  It  is  commonly  removed  by  hand,  and  makes  excellent 
firewood,  and  trunks  of  sufficient  size  and  straightness  are  used 
as  fence  posts.  The  stumps  and  roots  do  not  decay  rapidly 
and  are  generally  grubbed  by  hand,  which  is  laborious  and 
expensive. 


PREPARATION  OF  LAND  FOR   IRRIGATION  105 

Juniper  and  Pinon  trees  are  numerous  in  middle  latitudes 
and  altitudes,  and  merchantable  pine  trees  sometimes  occur  on 
land  destined  for  irrigation.  The  long  leaf  pines  may  furnish 
saw  logs  of  value,  but  the  Pinon  is  of  value  only  for  fuel. 

Juniper  (sometimes  called  cedar)  often  sends  many  heavy 
branches  from  one  root  at  the  ground,  and  all  these  must  be  cut. 
The  stumps  do  not  readily  decay,  and  are  difficult  to  grub.  The 
cost  of  clearing  is  therefore  greater  than  in  the  case  of  pines. 
Juniper  is  much  used  for  fence  posts,  which  are  very  durable. 

Where  the  soil  is  sandy  and  likely  to  blow  when  the  brush 
covering  is  removed,  the  clearing  must  be  performed  with  great 
care  and  caution.  It  should  never  be  attempted  in  the  spring 
or  at  any  season  when  high  winds  are  to  be  expected.  In  most 
localities  late  summer  is  the  best  season  in  this  respect.  Not 
all  of  the  ground  should  be  cleared  in  one  season,  but  where  the 
topography  will  permit  the  land  should  be  divided  into  strips 
about  40  feet  wide,  and  only  alternate  strips  cleared,  the  brush 
being  left  on  the  intervening  strips  as  a  protection  against  wind. 
As  soon  as  cleared,  each  strip  should  be  leveled  as  quickly  as 
possible,  and  immediately  irrigated  and  seeded.  Rye  or  wheat 
are  good  crops  to  seed  first,  as  they  sprout  and  cover  the  ground 
quickly,  grow  late  in  the  fall,  and  start  early  in  the  spring.  If 
possible,  immediately  after  seeding  a  liberal  sprinkling  of  straw 
should  be  spread  over  the  ground  and  a  disk  harrow  run  over  it, 
with  the  disks  vertical.  This  will  force  the  straw  partly  into 
the  ground,  leaving  the  ends  sticking  up  like  a  stubble.  This 
will  tend  to  prevent  drifting  until  the  grain  can  cover  the  ground. 

Alfalfa  may  be  seeded  at  the  same  time,  and  the  rye  or 
wheat  then  serves  as  a  nurse  crop,  to  protect  against  drifting, 
and  by  the  time  the  grain  matures  the  alfalfa  should  be  large 
enough  to  care  for  itself.  One  year  later  than  the  first  seeding 
the  intervening  strip  on  which  the  brush  was  left  may  be  cleared, 
leveled  and  seeded  in  the  same  way.  Water  must  be  used 
rather  freely  the  first  year  or  two,  and  means  should  be  pro- 
vided for  using  this  in  large  heads,  so  that  it  may  be  run  over 
the  ground  quickly,  before  that  first  applied  sinks  below  the  root 
zone.  In  such  sandy  regions  it  is  well  to  cover  the  ditch  banks, 


106  IRRIGABLE  LANDS 

roadsides,  and  all  other  unoccupied  areas,  with  vegetation  of 
some  kind  to  prevent  drifting  of  the  sand.  Rye  is  excellent 
for  this  purpose,  as  it  stands  drought  well,  reseeds  itself,  and 
never  becomes  a  pest.  Alfalfa  serves  the  purpose  even  better 
than  rye,  but  requires  more  water,  especially  in  youth.  As 
soon  as  a  good  stand  of  alfalfa  is  secured,  no  further  trouble 
need  be  encountered  with  that  particular  land,  but  it  may  still 
be  subject  to  danger  from  the  drifting  of  sand  from  neighboring 
fields.  One  or  two  ignorant,  careless  or  unskillful  farmers  can 
cause  their  neighbors  immense  damage  by  clearing  and  plowing 
their  land  and  leaving  the  soil  to  drift,  filling  laterals  and  roads, 
and  covering  other  fields  with  unwelcome  sand  dunes.  No 


FIG.  26. — Slip  Scraper. 

legal  remedy  has  been  provided  for  such  offenses,  and  it  is  neces- 
sary to  give  timely  expert  advice  and  exert  all  possible  moral 
pressure  to  see  that  the  advice  is  carefully  followed. 

The  cost  of  clearing  mescjuite,  pines,  juniper,  cottonwood, 
etc.,  varies  widely  with  the  size  and  density  of  the  growth, 
and  the  thoroughness  with  which  it  is  done.  Where  the  growth 
is  small  and  sparse,  and  grubbing  is  unnecessary,  as  on  arid 
benches,  mesquite  and  pinon  may  sometimes  be  removed  for 
$10  per  acre,  while  the  heavy  timber  may  run  in  some  cases 
considerably  above  $100  per  acre.  While  some  use  can 
usually  be  made  of  the  wood,  its  value  rarely  approaches  the 
cost  of  clearing,  and  is  generally  but  a  small  percentage 
thereof. 


PREPARATION  OF  LAND  FOR  IRRIGATION  107 

b.  Leveling. — It  is  seldom  that  in  its  natural  state  irrigable 
land  has  an  entirely  smooth  and  even  surface,  and  though  to  the 
unpracticed  eye  it  may  appear  smooth,  it  generally  has  undula- 
tions, which,  however  slight,  interfere  with  the  even  application 
of  irrigation  water.  In  attempting  to  irrigate  such  land  with- 
out leveling,  the  farmer  will  find  that  the  water  tends  to  accumu- 
late in  the  depressions  and  over-irrigate  them,  while  the  ele- 
vated spots  receive  little  or  no  water.  Much  labor  is  expended 
in  trying  to  secure  uniform  distribution  of  the  water,  and  the 
results  are  not  satisfactory.  Failure  to  properly  level  the 
land  is  one  of  the  commonest  errors  of  beginners  under  irriga- 
tion, and  is  often  fatal  to  success. 


FIG.  27.— Adjustable  V  for  Making  Head  Ditches. 

It  is  not  desirable  to  make  the  land  a  dead  level,  but  to 
give  it  generally  a  smooth  plane  surface  with  slopes  either 
uniform  or  varying  to  suit  the  mode  of  irrigation  adopted.  If 
the  natural  slope  is  considerable,  and  the  furrow  method  of 
irrigation  is  to  be  used,  perfect  smoothness  is  not  so  important 
as  with  other  methods  of  irrigation,  but  is  still  desirable. 

Apparent  smoothness  sometimes  leads  the  farmer  to  believe 
that  no  leveling  is  necessary,  but  this  is  seldom  the  case. 
More  frequently  the  cost  of  proper  leveling  is  the  most  important 
item  in  the  preparation  of  the  land  for  irrigation,  and  it  is  a 


108 


IRRIGABLE  LANDS 


mistake  to  plant  orchards,  alfalfa  or  other  perennials  until  this 
is  thoroughly  done,  or  to  plant  any  crop  without  a  fair  degree  of 
leveling.  If  any  great  amount  of  leveling  is  necessary,  the 
mounds  must  be  scraped  off  and  the  soil  used  to  fill  the  hollows, 
and  after  a  year  of  irrigation,  it  may  be  found  that  the  new 
ground  has  settled,  and  further  work  must  be  done  to  achieve 
satisfactory  results.  For  this  reason,  it  is  often  best  to  plant 


FIG.  28. — Leveling  New  Land.     Idaho. 

some  annual  crop,  as  grain,  or  still  better  a  row  crop  like  beans, 
on  which  the  furrow  method  of  irrigation  can  be  used. 

The  amount  and  character  of  leveling  required  varies 
somewhat  with  the  method  of  irrigation  proposed.  The  furrow 
method  can  be  used  with  less  careful  leveling  than  any  of  the 
flooding  methods,  provided  the  slope  is  ample  to  force  the 
water  through  the  furrows,  and  provided  some  pains  are  taken 
to  make  the  bottom  of  the  furrow  more  uniform  in  slope  than 
the  ground  surface,  by  deepening  the  furrow  across  mounds, 
and  making  it  shallower  across  depressions. 


PREPARATION  OF  LAND  FOR  IRRIGATION  109 

When  the  border  system  is  used,  the  ground  between  borders 
should  have  a  uniform  slope  parallel  to  the  borders,  and  per- 
fectly level  transverse  thereto.  This  will  make  each  border  a 
miniature  terrace,  to  correspond  to  the  slope  of  the  head  ditch, 
and  will  minimize  the  labor  of  irrigation.  If  the  check  system 
is  to  be  used  it  will  result  in  miniature  terraces  in  both  directions. 
It  will  be  seen  that  it  is  important  to  have  in  mind  the  system 
to  be  used,  before  the  leveling  is  done. 

The  scraping  down  of  mounds  and  the  filling  of  hollows  is 
best  accomplished  with  the  Fresno  scraper,  shown  in  Fig.  29. 
Its  adjustments  are  such  that  it  may  be  made  to  take  off  a 


FIG.  29. — Fresno  Scraper. 

thick  or  thin  coat  of  earth,  and  in  dumping  the  load,  it  can  be 
made  to  spread  the  earth  in  as  thin  a  layer  as  desired,  and  to 
leave  it  fairly  level.  These  are  important  advantages  peculiar 
to  this  implement.  The  Fresno  can  be  used  for  hauls  of  any 
distance,  but  it  is  not  very  advantageous  for  long  hauls.  It  is 
also  suitable  for  making  ditches,  dikes,  and  any  other  scraper 
work  where  the  haul  is  not  great  enough  to  require  wheels. 
The  final  leveling  may  be  accomplished  by  a  cheap  device 
called  a  "  float,"  drawn  by  three  or  four  horses.  (Fig.  30.) 

Where  the  leveling  is  merely  local  and  no  haul  required, 
the  ordinary  road  machine  on  four  wheels  carrying  an  adjust- 
able blade  is  sometimes  used,  and  is  very  useful  where  available. 


110  IRRIGABLE  LANDS 

The  cost  of  leveling  varies  from  a  few  cents  per  acre  to  the 
maximum  amount  that  can  be  afforded,  and  depends  on  the 
amount  of  dirt  and  the  distance  it  has  to  be  moved.  In  some 
localities  the  cost  of  leveling  determines  whether  land  is  irrigable 
or  non-irrigable,  and  cases  occur  where  from  $60  to  $75  per 
acre  is  spent  on  leveling  alone.  On  steep  hillsides  successful 
irrigation  may  require  the  surface  to  be  graded  into  terraces, 
and  in  Southern  California  several  hundred  dollars  per  acre  is 
sometimes  spent  on  .such  preparation. 


FIG.  30. — Float  for  Leveling  Irrigable  Lands. 

c.  Ditching. — Farm  laterals  must  be  provided  to  lead  the 
water  from  the  irrigation  system  to  the  high  point  or  points  on 
the  farm,  and  a  head-ditch  must  be  provided  to  conduct  the 
water  along  the  upper  edge  of  each  field.  Then  if  the  check 
or  border  methods  of  irrigation  are  to  be  used,  it  will  be  neces- 
sary to  provide  the  levees  needed.  Some  work  on  the  larger 
laterals  may  be  done  by  means  of  the  slip  scraper,  illustrated 
in  Fig.  26,  but  most  of  it  can  best  be  performed  with  a  plow 
and  a  V  or  crowder,  which  is  a  wooden  A  -frame,  shod  with 
iron  and  steel  drawn  by  two  or  three  horses.  It  can  be  easily 
made  on  the  farm  of  standard  materials  found  in  any  town, 
and  is  very  useful  not  only  in  irrigation,  but  for  road  grading  as 
well.  See  Fig.  27. 


CHAPTER   IX 
APPLICATION  OF  WATER  TO  THE  LAND 

IN  A  few  cases,  under  special  conditions  water  is  applied  to 
plants  through  pipes,  by  sprinkling  or  otherwise,  as  in  the 
irrigation  of  city  lawns,  and  some  flower  and  vegetable  or  iruit 
gardens.  A  few  orchards  are  supplied  from  subterranean  pipes 
with  a  spigot  at  each  tree.  These  methods  are  expensive  and 
exceptional  and  are  employed  only  on  a  relatively  small  scale. 
More  than  99  per  cent  of  the  application  of  water  in  irrigation 
is  from  open  canals  and  laterals,  although  the  conveyance  of 
water  in  cement  pipes  to  avoid  percolation  losses  is  growing 
as  the  value  of  water  increases  in  various  localities  under  special 
conditions. 

i.  Methods  of  Irrigation. — The  usual  methods  of  applying 
water  to  land  may  be  divided  into  two  general  systems  namely: 
the  flooding  system  and  the  furrow  system.  Each  of  these 
general  systems  may  in  turn  be  subdivided  into  two  special 
methods,  thereby  constituting  four  methods,  more  or  less 
distinct,  as  follows: 

1.  Free  Flooding. 

2.  Flooding  between  Borders. 

3.  Furrow  Irrigation. 

4.  Corrugation  Method. 

a.  Free  Flooding. — This  method  is  the  earliest  and  crudest 
method  of  applying  water.  When  carelessly  employed  it  is 
wasteful  of  water  and  secures  indifferent  results,  being  apt  to 
slight  certain  parts  of  the  field,  and  over-saturate  other  parts; 
but  when  applied  with  skill  and  care  good  results  can  be  secured. 
This  system  is  applied  by  providing  sublaterals  on  contours 
across  the  field  on  a  fall  of  from  i  to  3  feet  per  thousand,  and 
leveling  the  field  between  these  sublaterals.  To  apply  the 

ill 


112  APPLICATION  OF  WATER   TO   THE  LAND 

water,  a  temporary  dam  of  wood  or  canvas  is  inserted  in  the 
ditch,  causing  it  to  overflow  on  the  lower  side,  or  to  discharge 
its  water  through  openings  in  the  lower  bank;  and  shovel  in 
hand,  the  irrigator  coaxes  the  water  to  all  parts  of  the  ground, 
leading  it  to  the  dry  places  by  clearing  away  obstructions,  and 
checking  it  with  shovels  of  dirt  where  it  runs  too  freely.  If 
the  field  be  carefully  leveled,  the  ditches  carefully  located  and 
constructed,  and  the  irrigator  uses  sufficient  skill,  large  heads  of 
water  may  be  used,  very  good  results  may  be  obtained  and  a 
field  may  be  thus  irrigated  very  quickly. 

In  a  modification  of  the  free  flooding  method  commonly  used 
on  steeper  ground  than  the  method  just  described,  a  series  of 
dikes  on  contours  are  provided  roughly  parallel  to  the  lateral, 
and  the  ground  above  the  dike  is  leveled  so  that  it  can  be 
readily  flooded.  Another  dike  below  the  first  facilitates  the 
flooding  of  a  lower  level,  each  dike  forming  a  small  terrace.  This 
may  be  extended  down  the  hill  to  several  levels,  the  water  being 
drawn  from  one  level  to  the  next  lower  through  a  pipe  or  tile, 
or  carried  down  in  a  small  sublateral.  This  system  merges  into 
the  terrace  system  common  in  hilly  countries,  especially  in  India 
and  China,  and  to  a  Limited  extent  in  Southern  California. 

b.  Flooding  between  Borders. — In  this  system  parallel  dikes 
are  provided  running  nearly  normal  to  the  farm  laterals,  generally 
down  the  steepest  slope  of  the  field,  which,  however,  should 
not  exceed  4  or  5  feet  per  thousand.  These  dikes,  usually  called 
"  borders  "  are  from  40  to  60  feet  apart,  and  5  to  8  inches  high, 
with  gentle  side  slopes,  forming  gentle  undulations  over  which 
machinery  can  pass  with  ease.  The  border  should  not  be  more 
than  400  or  500  feet  long,  to  the  next  cross  lateral  below,  and  in 
flat  country  may  be  from  200  to  300  feet.  The  steeper  the 
slope,  the  longer  and  narrower  may  be  each  "  land,"  or  "  strip." 

To  apply  the  water  the  lateral  is  obstructed  by  a  temporary 
dam  at  the  second  "  border  "  at  the  top  of  the  field,  causing 
the  lateral  to  overflow  uniformly  between  the  first  and  second 
borders.  If  the  ground  is  properly  leveled  and  an  ample 
head  is  used,  the  water  flows  slowly  and  uniformly  several 
inches  deep  between  these  borders  as  in  a  broad  shallow  canal  to 


METHODS  OF  IRRIGATION 


113 


the  lower  end  of  the  strip.  When  a  sufficient  amount  of  water 
has  been  turned  on  to  the  strip  to  thoroughly  wet  it  to  the 
lower  end,  the  temporary  dam  is  removed  from  the  head  of  the 


FIG.  31. — Using  Canvas  Dam. 

second  border,  and  placed  in  the  lateral  at  the  head  of  the 
third  border,  causing  the  lateral  to  overflow  between  the  second 
and  third  borders,  and  this  process  is  repeated  across  the  field. 


FIG.  32. — Steel  Dams. 

Experience  will  soon  teach  the  irrigator  to  judge  closely  when 
enough  water  is  started  down  the  strip  to  accomplish  its  mission 
without  the  waste  of  much  water,  or  the  over-irrigation  of  any 


114 


APPLICATION  OF  WATER   TO   THE  LAND 


part  of  the  strip.  Skillfully  employed,  with  large  heads  of 
water,  land  properly  leveled,  and  laterals  properly  constructed, 
this  method  secures  good  results,  and  is  the  most  expeditious  of 
all  the  methods  here  described,  provided  the  topography  and 
slope  are  favorable. 

To  secure  good  results  economically,  this  system  requires 
careful  and  thorough  preparation  of  the  field.  There  should 
be  no  side  slope  between  the  borders,  so  there  will  be  no  tendency 


FIG.  33. — Diverting  Water  from  Head  Ditch  by  Canvas  Dam,  Shoshone  Valley, 

Wyoming. 

of  the  water  toward  one  side  of  the  strip.  Provision  should 
always  be  made  so  that  the  waste  water  at  the  lower  end  of  the 
strip  shall  be  received  into  the  next  cross  lateral  and  utilized  in 
irrigating  the  lower  lands.  The  strip  should  be  of  such  length, 
and  the  head  of  water  used  of  such  volume  that  the  water  will 
reach  the  lower  end  of  the  strip  before  much  water  has  time  to 
waste  into  the  subsoil  on  the  upper  end  where  it  is  turned  on. 
Thus  the  details  must  be  worked  out  with  reference  to  the 
character  of  the  soil,  the  slope,  and  the  head  of  water  available. 


METHODS  OF  IRRIGATION 


115 


The  border  system  is  especially  recommended  for  the  irriga- 
tion of  open  sandy  soils,  because  it  is  the  system  best  adapted 
to  the  safe  and  economical  use  of  large  irrigating  heads.  If 
small  quantities  of  water  are  turned  on  very  loose  sandy  soils, 
the  rapid  downward  movement  absorbs  so  much  water  that  little 
is  left  to  flow  to  the  lower  end  of  the  field,  and  it  moves  along 
the  ground  so  slowly  that  the  major  portion  of  the  water  is  lost 
by  dropping  below  the  plant  roots.  A  larger  quantity -applied 


FIG.  34. — Drawing  Water  from  Head  Ditch  through  Small  Pipes,    Riverside, 

California. 

to  the  same  ground  percolates  downward  as  fast  but  no  faster, 
but  by  its  volume,  moves  rapidly  over  the  field,  and  the  irriga- 
tion is  accomplished  before  much  water  is  lost,  provided  the 
ground  is  well  prepared  and  the  irrigation  performed  with 
skill.  Previous  preparation,  however,  is  very  important. 

Experiments  on  sandy  land  near  Hermiston,  Oregon,  in  the 
Umatilla,  Valley  illustrate  this  fact:  Two  tracts  of  land  of  the 
same  size  on  similar  soil  were  irrigated  by  the  same  man,  using 


116 


APPLICATION  OF  WATER  TO  THE  LAND 


35-— Field  Prepared  for  Irrigation  by  Checks. 


FIG.  36. — Border  Irrigation  in  Nevada. 


METHODS  OF  IRRIGATION 


117 


PLAN 


, 


II 


; 
=  I 

in 


a  head  of  3^  cubic  feet  of  water  per  second.  To  the  first  plot 
3.5  inches  of  water  was  applied  in  one  hour,  and  it  was  well 
irrigated.  To  the  second  tract  16.8  was  applied,  which  required 
4!  hours  of  labor,  to  accomplish  the  irrigation.  The  first  field 
was  bordered  and  well  leveled,  with  turnouts  of  good  size. 
The  second  field  was  irri- 
gated by  free  floodings,  and 
had  not  been  properly 
leveled.  Its  irrigation  cost 
for  labor  and  water,  4!  times 
as  much  as  the  first  field, 
and  the  results  were  not  so 
good. 

c.  Furrow  Irrigation.— 
This  system  is  specially 
adapted  to  the  irrigation 
of  crops  growing  in  rows, 
though  it  can  be  also  ap- 
plied to  others.  It  provides 
for  turning  the  water  into 
furrows  which  run  across 
the  field  in  the  direction 
of  greatest  slope  unless  this 
is  excessive,  in  which  case 
they  should  follow  the  grade 
on  which  a  furrow  full  of 

water  will  run  freely  without     FlG-   37-— Diagram   Illustrating   Flooding 
mi      r  u      u  in   Rectangular   Block.     Cowgill. 

erosion.    The  furrows  should 

be  from  2  to  4  feet  apart,  depending  upon  the  slope  and 
the  nature  of  the  soil.  If  the  slope  is  steep  and  the  soil 
relatively  tight,  they  must  be  closer  than  under  the  reverse 
conditions,  as  the  subsurface  of  the  ground  between  the  furrows 
must  all  be  thoroughly  wetted  by  the  time  the  irrigation  is 
completed.  The  water  is  allowed  to  run  in  each  furrow  until 
there  is  sufficient  to  run  through  to  the  lower  end,  which  is 
generally  a  distance  of  200  to  400  feet  to  the  next  cross  ditch. 
Furrow  irrigation  is  better  adapted  than  the  flooding  methods 


118 


APPLICATION  OF   WATER   TO   THE  LAND 


i 

1 


METHODS  OF  IRRIGATION 


119 


to  undulating  fields  and  steep  slopes,  upon  which  the  furrows'  can 
follow  such  lines  as  will  secure  the  most  desirable  grades.  It 
also  secures  a  thorough  wetting  of  the  root  systems  of  the  crops, 
without  wetting  the  top  of  the  ground  except  in  the  furrows 
and  thus  to  some  extent  avoids  baking.  It  has  a  tendency  to 
encourage  deep  rooting,  and  does  not  promote  shallow  rooting 
as  do  flooding  methods  of  application.  After  furrow  irrigation 


FIG,  39. — Furrow  Irrigation  of  Cabbages,  Yuma,  Arizona. 


it  is  practicable  to  get  over  the  ground  sooner  with  a  cultivator, 
which  is  very  desirable.  For  these  reasons  if  skillfully  used 
it  is  more  economical  of  water  than  the  flooding  methods. 
The  size  and  length  of  the  furrows  will  depend  upon  the  soil 
and  slope,  the  closer  soils  and  steeper  slopes  permitting  longer 
furrows  between  cross  laterals. 

d.  Corrugation  System. — This  is  a  modification  of  the  fur- 
row system  that  combines  some  of  the  features  of  the  flooding 
methods  also.  It  is  generally  an  adaptation  of  furrow  irriga- 


120 


APPLICATION  OF  WATER   TO  THE  LAND 


tion  to  crops  not  planted  in  rows,  such  as  grain  and  alfalfa, 
and  is  more  applicable  to  rolling  topography  than  the  flooding 
methods  proper. 

After  proper  leveling  of  the  minor  inequalities  of  the  sur- 
face, usually  immediately  after  planting,  while  the  ground  is 
soft,  a  series  of  parallel  grooves  are  made  with  a  machine  con- 
structed for  the  purpose,  resembling  a  short  wide  sled  with 
several  runners,  each  of  which  makes  a  groove  in  the  soft  ground, 


FIG.  40. — Furrow  Irrigation  on  Terraced  Hillside,  California. 

several  inches  in  depth,  from  2  to  3  feet  apart,  depending  on 
the  soil  and  slope,  the  closer  spacing  being  required  by  tight 
soil  and  steep  slope.  The  grooves  are  longitudinally  given  a 
gentle  grade,  so  as  to  conduct  the  water  gently  along  in  the 
direction  required,  and  prevent  it  running  down  the  steepest 
slope,  so  as  to  avoid  erosion. 

e.  Leveling. — All  these  methods  of  applying  water  to  land 
require  thorough  and  careful  preparation  for  the  best  results, 
especially  the  leveling  of  the  surface  inequalities. 


METHODS  OF  IRRIGATION 


121 


122 


APPLICATION  OF  WATER  TO  THE  LAND 


FIG.  42. — Orange  Trees  Irrigated  by  Check  System,  Salt  River  Valley,  Arizona. 


FIG.  43. — Furrow  Irrigation  of  Orange  Grove,  Riverside,  California. 


SEWAGE  DISPOSAL 


123 


2.  Sewage  Disposal.— One  of  the  most  important  and 
difficult  problems  with  which  municipal  engineers  have  to 
deal  in  that  of  sewage  disposal.  In  the  humid  regions  where 


Ft. 


0  1  2   3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18  19  20 


3        4 


7       8       9      10     11     12      13     14      15     16      17     18      19     20, 


5         f,         7         8         9        10       11       12       13       14       15       1C       17       IS 


FIG.  44. — Extent  of  Percolation  from  Small  Furrows:   A,  in  Loose  Loam;    B,  in 
Hardpan;    C,  in  Impervious  Grit. 

the  large  cities  are  usually  found  very  close  to  rivers  of  some 
magnitude  or  near  the  ocean,  the  sewage  has  usually  been  dis- 
posed of  by  discharging  it  into  the  natural  waterways  and 
allowing  it  to  be  carried  off  to  the  ocean,  more  or  less  of  the  im- 


124 


APPLICATION  OF  WATER   TO  THE  LAND 


SEWAGE  DISPOSAL 


125 


FIG.  46. — Irrigating  Cora  with  Sewage,  Plainfield,  New  Jersey. 


FIG.  47. — Furrow  Irrigation  of  Apple  Orchard,  Idaho. 


126  APPLICATION  OF  WATER   TO   THE  LAND 

purity  being  removed  first,  in  many  cases.  In  the  arid  regions, 
this  method  of  disposing  is  not  so  easy  of  accomplishment, 
because  of  the  lack  of  waterways  into  which  to  discharge  it. 
Difficulties  have  also  been  encountered  in  the  older  inhabited 
portions  of  the  country,  because  of  the  large  amounts  of  sewage 
contributed  by  the  dense  population  at  short  intervals  along 
the  waterways  carrying  small  quantities  of  water. 

Because  of  the  difficulties  of  disposing  of  sewage  by  dilution 
just  referred  to,  and  in  some  cases  with  the  idea  of  utilizing 
the  fertilizing  properties  of  sewage,  other  methods  of  disposing 
of  sewage  have  been  employed,  most  of  them  recently  developed. 
However,  the  use  of  sewage  for  irrigating  land  has  been  employed 
for  centuries.  The  sewage  of  Edinburgh  has  been  so  used 
for  an  unknown  number  of  years,  certainly  several  hundred, 
and  in  the  Craigentinny  meadows,  originally  a  waste  of  sand 
dunes,  250  acres  irrigated  with  sewage  have  been  yielding  crops 
of  hay  and  Italian  rye  grass  for  one  hundred  and  fifty  years.  In 
1858  the  first  scientific  investigation  of  this  use  of  sewage  was 
made  in  England,  and  a  number  of  English  towns  began  to 
construct  sewage  farms.  One  of  the  areas  was  at  Aldershot, 
constructed  in  1864,  where  the  sewage  of  20,000  people  is  used 
for  irrigating  about  120  acres.  The  soil  here  is  coarse  sand 
with  a  very  fine  sand  subsoil. 

In  this  country  irrigation  was  employed  in  a  number  of 
Eastern  cities  shortly  after  1870,  but  has  been  practically  aban- 
doned in  the  Eastern  States.  On  the  other  hand,  it  has  been 
increasing  in  arid  sections  of  Western  ones.  At  the  present  time 
(1918)  there  are  known  to  be  thirty  cities  and  towns  in  Cali- 
fornia that  dispose  of  their  sewage  by  irrigation,  one  in  Arizona, 
one  in  Kansas,  two  in  Oregon,  and  three  in  Montana.  In  the 
Eastern  States  there  are  believed  to  be  only  eighteen  cities  or 
towns  where  sewage  irrigation  is  practiced,  three  in  Connecticut, 
one  in  Massachusetts,  one  in  New  York,  nine  in  New  Jersey, 
two  in  Pennsylvania,  and  two  in  Virginia. 

A  process  very  similar  to  irrigation  is  used  for  disposing 
of  sewage  known  as  ''intermittent  filtration";  in  fact,  it  is 
difficult  to  draw  the  line  sharply  between  the  two.  In  inter- 


SEWAGE  IRRIGATION  127 

mittent  filtration  the  sewage  is  run  over  the  land  for  a  short 
period  and  then  the  flooding  ceases  while  the  land  absorbs 
and  digests  the  sewage  already  received;  then,  after  a  brief 
rest,  the  same  land  is  again  flooded.  Ordinarily  no  crops 
are  grown  upon  such  land,  but  the  top  soil  is  kept  loose  so  as  to 
more  readily  absorb  the  sewage.  In  intermittent  filtration  the 
controlling  purpose  is  to  dispose  of  the  sewage  in  a  sanitary 
manner  and  to  produce  an  acceptable  effluent;  in  the  case  of 
irrigation  or  sewage  farming,  on  the  other  hand,  the  controlling 
purpose  is  to  utilize  the  sewage  to  the  best  advantage  in  raising 
crops,  purification  of  the  sewage  being  a  secondary  purpose. 

3.  Sewage  Irrigation. — The  utilization  of  sewage  by  broad 
irrigation  requires  the  employment  of  a  much  larger  tract 
than  for  intermittent  filtration,  one  acre  of  land  being  sufficient 
to  utilize  the  sewage  of  from  50  to  200  people,  while  intermittent 
filtration  on  favorable  soil  the  sewage  from  500  to  1500  people 
per  acre  can  be  purified.  If  it  is  desired  to  use  more  sewage 
in  irrigation  than  that  named  above,  this  is  possible,  but 
generally  only  at  some  sacrifice  to  the  best  results  from  the  crops. 

The  water  returned  by  the  soil  to  the  natural  drainage 
channels  is  pure  enough  to  be  harmless  for  any  purpose,  except 
for  human  consumption,  wherever  all  of  the  sewage  passes 
through  the  soil;  although,  of  course,  if  any  of  it  runs  over  the 
surface  into  the  drainage  channel,  such  purification  is  not 
obtained.  One  of  the  most  serious  objections  to  the  disposal 
of  sewage  by  irrigation  is  the  fact  that  the  farmer  must  take 
the  sewage  at  all  times,  even  though  he  has  more  than  he  wants 
and  it  injures  his  land,  unless  it  be  possible  for  him  to  waste 
the  sewage  directly  into  drainage  channels.  It  has  been  found, 
however,  that  a  combination  of  the  above  methods,  in  which 
intermittent  filtration  is  used  as  a  supplement  to  broad  irriga- 
tion, practically  overcomes  this  advantage  and  is  the  most 
satisfactory  method  of  disposing  of  and  utilizing  sewage  on  land. 
This  is  done  by  laying  out  a  small  portion  of  the  land  as  a  filter 
bed,  and  discharging  the  sewage  onto  this  at  such  times  as 
it  is  not  needed  in  irrigation.  Where  this  plan  is  practiced 
it  is  necessary  to  turn  the  sewage  onto  the  filter  beds  for  a  few 


128  APPLICATION  OF  WATER   TO   THE  LAND 

hours  at  a  time,  about  once  a  week,  in  order  to  keep  alive  in  the 
soil  the  purifying  bacteria. 

Irrigation  in  America  has  been  practiced  in  two  ways,  by 
broad  irrigation  and  by  subsurface  irrigation;  most  instances 
of  the  latter  use  having  occurred  in  the  Eastern  States. 

4.  The  Fertilizing  Effects  of  Sewage. — Sewage  used  for 
irrigating  acts  in  two  ways — supplying  water  to  the  soil,  as  in 
the  case  of  water  irrigation;  and,  besides,  contributing  fertilizing 
matter  to  the  soil.  Sewage  contains  varying  amounts  of  nitro- 
gen, potash  and  phosphates,  different  authorities  calculating 
that  the  amount  of  such  chemicals  in  1,000,000  gallons  of  sewage 
would  have  a  theoretical  value  of  from  $40  to  $125.  Some  of 
these  constituents,  however,  may  be  only  partly  available  for 
manurial  purposes,  or  may  be  carried  on  beyond  the  reach  of 
growing  crops  by  the  water  that  is  drained  from  the  soil.  Others 
may  be  retained  at  or  near  the  surface  and  later  penetrate 
the  soil  very  slowly  if  at  all.  Sewage  generally  contains  more 
or  less  grease,  which  tends  to  clog  the  pores  of  the  soil,  and  also 
filaments  of  cloth  and  paper,  match  sticks  and  other  insoluble 
materials  that  collect  on  the  surface  and  form  a  sort  of  mat. 
These  may  be  dug  under,  but  doing  so  is  of  doubtful  value. 

Experience  on  European  sewage  farms,  notably  at  Paris 
and  Berlin,  appears  to  indicate  that  farmers  are  willing  to  pay 
more  for  land  irrigated  with  sewage  than  for  that  which  is  not. 
In  this  country,  the  conclusion  seems  to  have  been  generally 
reached  that  sewage  is  of  little  if  any  more  value  for  irrigating 
than  is  plain  water,  but  on  the  other  hand,  it  is  not  considered 
to  be  less  valuable;  and  in  arid  districts  where  water  is  needed 
for  irrigating  and  where  sewage  can  be  used  for  this  purpose 
at  no  greater  expense  than  that  required  for  obtaining  other 
water,  irrigation  with  sewage  is  being  adopted  more  and  more 
generally.  One  of  the  latest  towns  to  take  up  sewage  irrigation 
was  Tucson,  Arizona,  where,  after  using  sewage  in  this  wray  on 
a  small  scale  for  seventeen  years,  arrangement  was  made  in  1918 
to  irrigate  483  acres  of  farm  land  with  the  sewage  of  the  city, 
for  which  the  city  is  receiving  about  $10  per  acre  per  year. 

All  kinds  of  vegetables,   grains,   and  trees  that  are  raised 


EFFECTS  OF  SEWAGE  IRRIGATION  ON  HEALTH  129 

by  irrigation  can  be  grown  on  sewage  farms;  but  lettuce, 
radishes,  berries  and  other  edible  vegetable  products  that  are 
eaten  raw  and  could  in  any  way  come  in  contact  with  the  sewage 
should  not  be  grown  on  such  farms  because  of  the  danger  that 
germs  in  the  sewage  might  cause  typhoid  fever  in  the  consumers 
of  the  products  of  the  farm.  An  epidemic  of  sixty- three  cases 
of  typhoid  fever  at  a  Massachusetts  insane  asylum  was  traced 
to  celery  fertilized  by  sewage.  On  the  Paris  farm  the  cultiva- 
tion of  strawberries,  salad  crops  and  other  vegetable  products 
that  are  freely  exposed  to  the  sewage  and  then  eaten  raw  is 
prohibited. 

5.  Effects  of  Sewage  Irrigation  on  Health. — Fears  are  some- 
times expressed  that  sewage  farms  would  be  dangerous  to  the 
health  of  the  neighboring  districts  and  that  crops  grown  on  them 
would  be  unwholesome.  These  fears,  aside  from  the  danger 
of  direct  contact  with  the  edible  parts  of  vegetables  referred  to 
above,  have  proven  groundless  and  sewage  farming,  while  it 
satisfies  the  sanitary  conditions,  at  the  same  time  gains  for 
agriculture  a  source  of  fertilizer  as  well  as  of  water  which  would 
otherwise  run  to  waste.  The  crops  themselves,  in  utilizing  the 
sewage,  transform  all  of  the  dangerous  and  objectionable  mat- 
ters, just  as  they  do  in  utilizing  manure  and  other  fertilizing 
materials.  There  is  therefore  no  danger  from  sewage  matters 
absorbed  by  the  plants. 

It  has  bsen  quite  fully  demonstrated  that  there  is  no  danger 
to  health  in  any  odors,  gases,  or  vapors  that  may  arise  from 
sewage  on  a  sewer  farm.  It  is  conceivable  that  disease  germs 
might  be  carried  from  the  sewage  by  flies  or  other  insects, 
but  experience  indicates  that  such  danger  is  very  slight,  there 
being  no  cases  on  record  of  disease  which  has  been  communicated 
in  this  way.  As  to  sewage  matters  which  may  be  deposited  on 
the  surface  of  the  soil,  thorough  tilling  of  the  soil  after  each 
flowing  of  sewage  is  essential,  and  it  is  by  the  creation  of  a 
proper  tilth  that  the  aeration  of  the  sewage  and  incorporation 
of  the  solid  matter  with  the  soil  is  accomplished.  This  prevents 
the  accumulation  of  sewage  matters  on  the  surface  and  further- 
more any  danger  to  the  salubrity  of  the  surrounding  country. 


130  APPLICATION  OF  WATER   TO   THE  LAND 

When  sewage  is  run  on  the  land,  there  is  at  times  a  perceptible 
and  faintly  disagreeable  odor,  especially  under  certain  atmos- 
pheric conditions,  but  this  odor  is  not  perceptible  more  than  a 
few  hundred  feet  away,  and  as  soon  as  the  soil  has  been  culti- 
vated it  entirely  disappears. 

6.  Duty  of  Sewage. — At  Pasadena,   California,  the  sewage 
of  6000  people  is  used  in  irrigating  about  40  acres  of  the  land, 
or   about    i    acre   to   each    150   inhabitants.     At   Los   Angeles 
(previous  to  the  abandonment  of  the  farm  and  the  carrying 
of  the  sewage  to  the  Pacific,  due  to  the  spread  of  the  city  over 
the    land    available    for    irrigation)    the    entire    sewage,    which 
averaged  105  second-feet  flowing  constantly,  was  used  in  irri- 
gating 17  acres.     This  is  the  sewage  of  50,000  people  and  it  was 
therefore  employed  at  the  rate  of  about  30  individuals  per  acre; 
also  at  the  rate  of  about  40  acre-feet  per  acre  per  annum.     On 
the  average,  possibly,  western  irrigated  land  uses  during  the 
irrigation  season  about  10,000  gallons  per  acre  per  day,  or  the 
sewage  of  about  80  persons  per  acre. 

Prof.  Wilson  has  stated  that  with  few  exceptions  the  irri- 
gating duty  of  sewage  is  less  than  that  obtainable  with  clear 
water,  raw  sewage  seldom  serving  more  than  one-third  to  one- 
half  as  much  area  as  the  same  quantity  of  clear  water,  owing  to 
the  surface  of  the  soil  being  clogged  by  the  solids  in  the  sewage, 
which  causes  much  of  the  water  to  run  off  without  soaking  in. 
This  disadvantage  can  be  removed  to  a  considerable  extent  by 
previously  clarifying  the  sewage,  removing  all  of  the  coarse 
suspended  matter.  The  objectionable  reduction  of  duty  by 
clogging  may  not  interfere  with  the  use  upon  the  land  of  as 
much  sewage  as  is  desired  for  crop  irrigation,  but  this  limitation 
may  become  objectionable  only  when  the  problem  is  one  of 
disposing  of  sewage  on  the  minimum  amount  of  land. 

7.  Methods   of   Laying   Out   Sewage   Farms   and  Applying 
Sewage. — In  preparing  land  for  sewage  irrigation  it  must  be 
remembered    that  the  sewage  cannot  be  disposed  of    continu- 
ously on  the  same  piece  of  land  with  benefit  to  crops,  but  that 
it  must  be  rotated  from  one  plot  to  another  so  as  to  give  each  a 
rest  and  permit  of  the  soil  being  cultivated  and  the  crops  handled. 


METHODS  OF  LAYING  OUT  SEWAGE  FARMS  131 

With  this  end  in  view,  it  has  been  found  that  the  most  'satis- 
factory way  of  laying  out  a  sewage  farm  is  to  divide  it  into 
many  very  small  tracts  or  plots  of  about  one  acre  in  extent  each, 
so  arranged  and  subdivided  by  distributing  channels  that  the 
sewage  may  be  applied  to  them  separately  and  independently. 
Experience  has  shown  that  first  of  all  the  soil  must  be  of  suitable 
texture,  and  care  should  be  taken  to  choose  a  location  in  which 
may  be  found  a  deep  and  light  surface  soil,  underlain  if  pos- 
sible by  a  deep  and  porous  subsoil,  preferably  of  sand  and 
gravel.  If  the  slopes  of  these  are  such  as  to  furnish  good  natural 
drainage,  no  difficulty  is  likely  to  arise  in  utilizing  such  land 
for  a  definite  period  of  time  under  proper  treatment. 

After  a  suitable  soil  has  been  chosen  and  the  land  has  been 
under  drained  or  otherwise  suitably  prepared,  it  should  be 
divided  by  open  drains,  preferably  lined,  into  plots  of  from 
200  to  400  feet  on  a  side.  The  sewage  should  be  brought  to 
the  limits  of  the  farm  in  closed  sewer  conduits,  which  must 
be  properly  ventilated.  It  is  desirable  at  the  outlet  of  the 
conduit  at  the  entrance  of  the  farm  to  construct  a  small  storage 
reservoir,  suitably  lined,  since  it  may  be  necessary  to  retain  the 
sewage  for  at  least  twenty-four  hours,  and  certainly  over  a 
night,  at  times  when  it  is  not  possible  to  use  it.  There  should 
also  be,  at  the  entrance  to  the  farm,  a  coarse  screen  to  keep 
out  the  larger  matters  in  the  sewage;  and  it  is  very  desirable 
there  should  be  in  addition  either  a  fine  screen  or  a  tank  adapted 
in  size  and  shape  to  secure  sedimentation  of  the  suspended 
matters  which  would  cause  the  clogging  of  the  surface  of  the 
irrigated  field.  The  matters  collecting  behind  the  coarse  screen 
may  be  placed  in  piles  to  dry  and  then  burned,  and  that  from 
the  fine  screens  or  settling  tank  may  be  removed  at  intervals 
and  either  plowed  under  the  soil  or  dried  and  burned.  The 
storage  tank  and  sedimentation  tank  (these  may  be  combined 
as  one  in  many  cases)  are  frequently  covered  to  prevent  dis- 
semination of  odors,  but  this  is  not  generally  necessary  unless 
the  sewage  reaches  the  farm  in  a  stale  condition,  or  the  tank  is 
so  constructed  or  operated  as  to  permit  deposits  to  collect 
about  it  and  putrefy. 


132  APPLICATION  OF  WATER   TO  THE  LAND 

The  most  satisfactory  way  of  applying  sewage  for  irrigation 
is  through  furrows  between  rows  of  vegetables,  the  simple 
furrow  method  of  irrigation  (page  117)  being  employed.  In 
some  cases,  however,  the  emb  nkment  or  check  method  has 
been  employed,  more  especially,  in  the  cultivation  of  grain 
and  forage  crops.  After  applying  sewage  to  crops  it  is  left 
only  so  long  as  to  permit  it  to  become  dry  enough  to  work 
when  the  land  is  thoroughly  tilled  and  all  solid  matter  is  turned 
under  before  the  next  application  of  sewage,  while  such  a  variety 
of  crops  must  be  employed  as  to  make  the  irrigation  season  as 
long  as  possible.  In  irrigating  walnut  groves  on  the  Pasadena 
farm,  the  sewage  is  allowed  to  run  on  one  area  from  four  to  ten 
days  and  is  then  turned  upon  another  area,  the  former  area 
being  thoroughly  cultivated  or  plowed  as  soon  as  it  is  sufficiently 
dry  to  work,  which  is  usually  within  two  or  three  days.  The 
top  soil  is  plowed  under  -occasionally,  but  not  after  each  flooding, 
only  a  thorough  stirring  with  a  cultivator  being  necessary  as  a 
regular  treatment. 

During  the  non-irrigating  period  (the  winter  months), 
the  sewage  may  be  flooded  in  rotation  over  various  plots  of 
land  and  be  permitted  to  filter  through  this  and  find  its  way 
back  to  the  natural  drainage  channels.  It  is  desirable,  however, 
to  use  precaution  and  not  overcharge  the  land,  and  this  may  be 
prevented  by  tilling  it  a  f  w  times  during  the  more  open  days 
of  winter.  As  soon  as  t  e  crops  are  to  be  sown  in  spring  it  is 
desirable,  should  too  great  an  accumulation  of  solid  matter 
appear  on  the  surface,  to  rake  this  off  or  plow  it  under  before 
planting  the  season's  crops.  Ordinarily  sewage  reaches  the 
irrigated  land  at  a  sufficiently  high  temperature  to  permit  it 
to  remain  unfrozen  and  to  find  its  way  by  filtration  into  the  soil 
even  during  the  winter;  but  in  Northern  climates  this  is  not 
always  the  case,  and  should  the  top  soil  once  become  frozen 
it  is  almost  impossible  to  thaw  it  again  before  spring.  To 
prevent  this,  it  is  desirable  when  cold  weather  is  anticipated 
to  plow  the  farm  into  furrows  about  18  inches  apart.  This 
prevents  the  rapid  chilling  of  the  sewage  that  occurs  when  it  is 
spread  in  a  thin  layer  exposed  to  the  air,  and  should  the  surface 
of  the  sewage  freeze,  the  bottom  of  the  furrow  would  still  remain 


SUBIRRIGATION  133 

unfrozen  and  would  be  protected  from  the  freezing  air  above 
by  the  ice  that  would  span  the  furrow  from  ridge  to 
ridge. 

8.  Subirrigation. — The  term  subirrigation  denotes  the  under- 
ground application  of  water  to  the  roots  of  plants,  as  dis- 
tinguished from  its  application  to  the  surface  of  the  ground. 

There  are  two  radically  different  methods  of  accomplishing 
this  result.  One  is  to  apply  water  to  a  portion  of  the  surface 
in  such  quantities  as  to  bring  up  the  ground  water  to  an  eleva- 
tion where  it  can  be  reached  by  the  roots  of  the  plants.  This 
is  called  "  bringing  up  the  sub."  It  is  a  pernicious  practice, 
very  wasteful  of  water  and  ruinous  to  the  land.  It  leaches 
out  the  plant  food,  it  waterlogs  large  areas  of  land  and  brings  to 
the  surface  whatever  alkali  the  soil  contains.  All  these  results 
tend  to  destroy  the  fertility  of  the  soil.  On  the  Egin'  Bench, 
in  the  Valley  of  the  North  Fork  of  Snake  River  in  Idaho,  the 
soil  is  very  coarse,  and  requires  frequent  irrigation  and  large 
quantities  of  water  if  surface  irrigation  is  practiced.  The  water 
supply  is  copious  in  May  and  June,  but  the  river  declines 
rapidly  in  July  producing  a  shortage  in  August.  The  farmers 
on  this  bench  have  formed  a  practice  of  "  bringing  up  the  sub." 
every  spring.  Water  is  applied  copiously  in  large  ditches 
and  by  surface  irrigation  during  May  and  June,  while  water 
is  abundant,  and  after  the  river  has  declined  the  ground  water 
remains  high  for  several  weeks,  furnishing  water  for  the  plant 
roots  for  a  much  longer  period  than  if  surface  irrigation  had 
to  be  depended  upon.  As  the  subsoil  is  open,  and  has  outlets 
to  the  bottom  lands  and  into  drainage  lines,  the  ground  water 
drains  out  to  the  early  fall,  and  the  fall  and  winter  precipitation 
passing  downward,  counteract  any  tendency  to  rise  of  alkali. 

The  peculiar  conditions  on  the  Egin  Bench  .render  this 
method  a  success  although  of  course  much  plant  food  is  carried 
away  by  the  excess  waters.  This,  however,  is  the  only  case 
known  to  the  writer  where  "  bringing  up  the  sub,"  can  be 
considered  anything  but  a  pernicious  practice. 

In  the  San  Luis  Valley  in  Southern  Colorado,  where  bringing 
up  the  ground  water  by  copious  irrigation  was  deliberately 
practiced  for  years,  the  result  has  been  the  ruin  of  hundreds  of 


13-4  APPLICATION  OF  WATER   TO   THE  LAND 

thousands  of  acres  of  fertile  land  by  water-logging  and  alkali, 
and  has  depopulated  many  towns  and  rural  districts  like  a 
pestilence.  A  cure  will  involve  an  expensive  drainage  system, 
and  the  adoption  of  more  rational  methods  of  irrigation. 

In  many  regions  ground  water  is  raised 'by  wasteful  methods 
of  irrigation,  without  any  intent  to  subirrigate,  but  the  result 
is  the  same,  the  rise  of  alkali  and  the  swamping  of  the  low- 
lying  lands;  in  such  regions  there  may  be  considerable  areas 
where  the  ground  water  is  nearly  stationary,  at  about  the  right 
elevation  to  serve  the  plants  without  the  surface  application 
of  water.  This  may  be  convenient  for  a  time,  but  the  constant 
upward  percolation  of  water  from  the  level  of  saturation  to 
supply  the  draft  of  plant  consumption  and  evaporation  soon 
brings  to  the  surface  whatever  alkali  is  in  the  soil,  and  if  this  is 
considerable  eventually  destroys  its  fertility. 

a.  Pipe  Irrigation. — The  application  of  water  to  the  roots  of 
plants  underground,  without  bringing  up  the  ground  water, 
by  means  of  pipes,  is  the  true  method  of  subirrigation,  and  may 
be  made  more  economical  of  water  than  surface  irrigation, 
for  it  reduces  evaporation  from  the  surface,  and  also  obviates 
the  losses  due  to  percolation  from  unlined  ditches. 

In  regions  where  water  is  valuable,  it  is  becoming  more  and 
more  the  practice  to  line  canals  and  laterals  with  cement,  or  to 
use  pipe  for  distributaries  instead  of  unlined  ditches,  which 
often  waste  large  quantities  of  water  by  seepage,  especially 
in  sandy  ground.  The  tile  method  of  subirrigation  is  merely 
an  additional  step  in  this  method  of  water  conservation. 

The  head  ditches  or  "  mains  "  may  consist  of  vitrified  clay 
tile  4  or  5  inches  in  diameter  with  bell  joints,  sealed  with  cement. 
They  should  be  located  along  the  upper  side  of  the  field,  or 
better  still,  should  follow  the  crest  of  a  ridge,  so  as  to  irrigate 
in  both  directions.  Branches  which  are  to  conduct  the  water 
to  the  plants,  are  of  smaller  vitrified  tile,  usually  about  3  inches 
in  diameter,  and  laid  with  open  joints  so  that  the  water  can 
escape  through  the  joint.  Each  joint  should  be  protected  by 
gravel  or  cinders,  from  entrance  of  sand  or  loam  that  would 
clog  the  pipe. 


SUBIRRIGATION  135 

At  each  point  where  an  open  joint  lateral  takes  out  from  the 
main,  there  should  be  a  stop-box.  This  consists  of  a  joint  of 
larger  pipe  placed  vertically  with  the  bottom  end  closed,  and 
the  upper  end  open.  Where  two  laterals  join  the  main  at  one 
point,  the  stop-box  should  be  placed  in  the  main,  but  where 
only  one  lateral  takes  out,  the  stop-box  should  be  at  the  side, 
and  not  interrupt  the  continuity  of  the  main.  Where  the 
lateral  or  the  main  takes  water  from  the  stop-box,  a  plug  or 
slide  should  be  provided  to  shut  off  the  water  when  desired. 
The  laterals  should  have  grades  not  over  4  inches  nor  less 
than  i  inch  per  100  feet,  and  should  be  from  12  to  15  inches 
below  the  surface,  or  joint  beyond  the  reach  of  the  plow,  and  in 
parallel  lines  15  to  20  feet  apart.  Both  the  depth  and  the  hori- 
zontal intervals  should  be  determined  experimentally  for  each 
combination  of  soil  and  topography.  Where  the  grade  is  more 
than  i  or  2  inches  per  100  feet,  it  is  best  to  place  stop-pockets 
in  the  lateral  at  intervals  of  200  to  400  feet  so  that  the  water 
can  be  checked  and  pressure  produced  to  force  the  water  out 
at  the  joints.  The  checking  is  best  performed  with  sliding 
gates  of  galvanized  iron.  The  length  of  time  and  amount  of 
water  required  for  a  proper  irrigation  varies  of  course  with 
the  soil,  the  slope  and  other  elements.  To  accomplish  the 
correct  degree  of  saturation  without  overdoing  it  requires 
great  care  at  first,  but  experience  with  a  particular  field 
system  soon  makes  it  much  easier.  It  should  be  the  aim  to 
bring  the  moisture  within  a  few  inches  of  the  surface,  but  not 
quite  to  the  surface.  Very  young  plants  require  the  moisture 
nearer  the  surface  than  older  ones  with  deep  roots,  and  as  the 
object  of  subirrigation  is  economy  of  water,  care  must  be  taken 
to  avoid  over  saturation,  and  escape  of  the  water  downward. 

In  Florida  and  other  humid  regions,  where  .irrigation  is 
practiced,  this  and  similar  methods  are  used  for  irrigation  during 
drought,  and  for  drainage  in  times  of  excessive  rainfall.  For 
such  double  use  it  is  necessary  to  place  the  tiles  considerably 
lower  in  the  ground  than  when  used  for  irrigation  alone. 

Underground  application  of  water  from  pipes  has  not  been 
extensively  practiced.  It  is  expensive,  and  has  not  achieved 


136  APPLICATION  OF   WATER   TO   THE  LAND 

the  economy  of  water  expected  by  some.  It  is  moreover,  sub- 
ject to  an  important  practical  difficulty.  The  roots  of  growing 
plants  are  apt  to  seek  the  openings  in  their  search  for  moisture, 
and  to  clog  them  and  cause  trouble.  This  is  less  apt  to  occur 
with  annual  than  with  perennial  plants  and  with  row  crops 
set  at  some  distance  from  the  pipes  than  with  those  sown 
broadcast. 

In  some  valuable  orchard  tracts  where  water  is  scarce  and 
costly,  it  is  conducted  in  iron  pipes  to  individual  trees  and  there 
delivered  by  a  branch  or  a  spigot,  above  the  surface  of  the  soil 
near  the  root  of  the  tree.  This  avoids  clogging  the  outlet  with 
roots.  A  modification  of  this  is  used  in  numerous  localities, 
mainly  in  humid  regions  for  truck  or  small  fruit  gardens,  where 
the  water  is  applied  under  pressure  to  the  pipes,  and  discharged 
in  an  overhead  spray.  In  other  cases  a  hose  is  used  manipulated 
by  hand. 

As  may  be  readily  seen,  all  pipe  systems  of  irrigation  are 
expensive,  and  practicable  only  for  intensive  cultivation  of 
valuable  crops.  The  chief  benefits  of  subirrigation,  however, 
can  be  obtained  more  economically  by  the  furrow  method  of 
irrigation  from  lined  laterals,  or  pipes,  and  hence  this  combina- 
tion is  the  one  most  generally  in  use  in  the  citrus  groves  of 
California,  where  irrigation  water  has  the  highest  value  attained 
in  any  important  district.  By  this  means  the  water  is  applied 
to  the  entire  root  zone,  without  wetting  any  of  the  surface 
except  in  the  furrows  and  immediately  adjacent  to  them. 

REFERENCES  FOR  CHAPTERS  VIII  AND  IX 

STANLEY,  F.  W.     Irrigation  in  Florida.     Bulletin  No.  462,  Office  of  Public  Roads 

and  Rural  Engineering,  Washington,  D.  C. 
TEELE,  R.  P.     Preparing  Land  for  Irrigation.     Year-book,  Dept.  of  Agriculture, 

1903. 
FORTIER,  SAMUEL.     Use  of  Water  in  Irrigation.     McGraw-Hill  Book  Company, 

New  York. 
ETCHEVERRY,  B.  A.      Use  of  Irrigation  Water.     McGraw-Hill  Book  Company, 

New  York. 
TAIT,  C.  E.     Use  of  Underground  Water  for  Irrigation  at  Pomona,  Cal.     Bulletin 

No.  236,  U.  S.  Office  of  Experiment  Stations. 


CHAPTER  X 
DUTY  OF  WATER 

IN  order  properly  to  plan  a  canal  system,  the  designer  must 
first  decide  upon  the  probable  "  Duty  of  Water  "  in  the  locality 
under  consideration. 

By  "  Duty  of  Water  "  is  meant  the  area  which  can  be  served 
by  a  unit  quantity  of  water.  This  may  be  expressed  in  two 
different  ways.  The  most  common  practice  is  to  speak  of  the 
area  that  can  be  served  by  a  running  stream  of  a  unit  volume, 
as  "  one  cubic  foot  per  second  will  serve  100  acres."  It  may 
also  be  expressed  as  the  depth  of  water  in  one  season  required 
by  the  land  in  question.  The  former  relation  is  the  one  necessary 
to  determine  the  area  that  can  be  served  by  a  natural  stream 
without  storage,  and  also  dictates  the  necessary  capacity  of  the 
canals.  But  when  water  is  dra\vn  from  a  storage  reservoir 
the  latter  relation  determines  the  area  that  can  be  served  by  a 
given  volume  of  stored  water. 

The  duty  of  water  has  been  the  subject  of  a  vast  amount  of 
study  and  much  valuable  data  has  been  published  regarding  it. 
Various  factors  affect  the  duty  of  water,  the  principal  ones  being 
these : 

1.  Length  of  season. 

2.  Natural  rainfall,  and  evaporation. 

3.  Soil  conditions. 

4.  Crops  raised.    * 

5.  Preparation  of  ground  and  ditches. 

6.  Skill  of  the  Irrigator. 

7.  Care  with  which  water  is  used. 

8.  Cultivation. 

Most  of  these  conditions  are  variable  and  are  not  susceptible 
of  accurate  determination  in  advance.  Nevertheless,  some  deci- 

137 


138  DUTY  OF  WATER 

sion  on  duty  of  water  must  be  reached,  if  we  are  to  build  an 
irrigation  system. 

i.  Length  of  Season. — The  arid  portion  of  North  America 
may  be  divided  roughly  into  three  general  types  as  regards 
length  of  season  and  requirements  for  irrigation  water,  based 
thereon. 

1.  The   northern  division  with   short   season,   cool  nights, 
and  cold  winters,  comprising  Canada,  Montana,  Wyoming  and 
the  Dakotas. 

2.  The   southern  division,  with  growing  season  nearly  or 
quite  the  year  round,  long  summers  and  mild  winters,  com- 
prising California,  Southern  Arizona  and  Mexico. 

3.  The    central    division,   with    growing   season   of   5   to   7 
months,  warm  summers  and  mild  but  frosty  winters,  comprising 
the  greater  part  of  the  rest  of  the  arid  region. 

Of  course,  these  divisions  merge  in  each  other,  and  two  classes 
are  often  represented  in  the  same  State.  For  example,  the  San 
Luis  Valley  in  Southern  Colorado  belongs  distinctly  in  the 
first  division  by  reason  of  its  high  altitude,  while  the  other 
principal  valleys  of  the  State,  although  further  north,  are  milder, 
and  belong  to  the  third  division.  Similarly,  other  localities 
may  not  belong  in  the  division  their  latitude  would  indicate. 

The  northern  division,  because  of  short  season,  requires 
less  water  than  the  others,  but  in  the  middle  of  the  season 
requires  a  greater  quantity  within  a  short  period  while  the 
crops  are  making  their  most  rapid  growth,  due  to  the  long  days 
of  midsummer,  while  the  hours  of  sunlight  are  at  their 
maximum.  Experience  shows  that  in  northern  regions  the 
delivery  capacity  of  the  irrigation  systems  must  be  larger  than 
is  required  in  the  more  southern  climes,  although  the  total 
quantity  of  water  delivered  during  the  season  is  much 
less. 

2.  Natural  Rainfall. — Any  precipitation  occurring  in  the 
growing  season  takes  the  place  of  a  certain  amount  of  irriga- 
tion water  that  would  otherwise  be  necessary.  Unless  the 
shower  occurs  just  after  an  irrigation  so  as  to  be  largely  super- 
fluous, or  is  so  heavy  that  much  of  it  runs  off  the  surface  or 


SOIL  CONDITIONS  139 

passes  away  through  the  subsoil,  the  rainfall  replaces  an  equal 
quantity  of  irrigation  water.  In  humid  regions  the  natural 
rainfall  is  sufficient  to  mature  good  crops  without  irrigation. 
In  semi-arid  regions  the  same  is  true  in  a  less  degree,  but  irriga- 
tion, if  feasible,  can  greatly  increase  the  yield.  In  the  arid 
regions  the  rainfall  may  be  anywhere  between  zero  and  twenty 
inches  in  the  growing  season,  and  of  course  its  amount  and  the 
time  and  manner  of  its  occurrence  profoundly  affect  the  quan- 
tity of  irrigation  required.  Even  the  precipitation  of  the  fall 
and  winter  months  has  an  important  effect  on  the  soil  moisture 
available  in  spring  and  summer,  especially  if  suitable  precautions 
are  taken  to  conserve  this  by  proper  cultivation.  But  as  the 
natural  rainfall  varies  from  year  to  year,  both  in  quantity  and 
in  time  of  occurrence,  it  is  necessary  to  consider  chiefly  the  years 
of  lowest  precipitation  when  planning  the  irrigation  system. 
The  water  evaporated  from  the  soil  is  of  course  not  available 
for  plants,  and  varies  widely  with  climate,  and  with  precautions 
to  conserve  it  by  cultivation. 

3.  Soil    Conditions. — As   we   have    seen    (Chapter   III),    a 
loose  sandy  soil  will  not  hold  as  much  water  as  one  of  closer 
texture,  and  if  the  subsoil  is  also  coarse  it  may  be  difficult  to 
apply   sufficient   water   for   plant   needs   without   large   losses 
through  the  subsoil.     Where  the  subdrainage  is  very  free  and 
the  soil  sandy  and  coarse,  the  temptation  to  over-irrigate  is 
very  great,  and  instances  are  known  where  farmers  have  applied 
sufficient  water  to  cover  the  land  to  a  depth  of  over  20  feet  in 
a  single  season  when  the  actual  needs  of  the  crop  were  perhaps 
only  10  or  15  per  cent  of  that  amount,  the  balance  escaping  to 
the  ground  water  table,  carrying  with  it  much  valuable  plant 
food,  and  injuring  neighboring  lands. 

4.  Crops  Raised. — Some  crops  require  less  water  -than  others. 
Grains,  for  example,  require  less  water  for  best  results  than 
alfalfa,  and  more  than  some  fruits.     It  is  therefore  necessary  to 
make  some  assumption  as  to  what  proportion  will  be  planted 
of  each  crop  adapted  to  the  region.     This  proportion  manifestly 
cannot  be  accurately  predicted,  and  is,  moreover,  sure  to  change 
with  time  in  a  manner  impossible  to  foretell. 


140  DUTY  OF  WATER 

5.  Preparation. — If  the  fields  be  not    properly  leveled,  an 
excess  of  water  must  be  applied  to  some  of  the  land  in  order  to 
wet  the  remainder,  and  much  may  be  wasted.      If  the   sub- 
laterals  and  farm  ditches  are  not  of  adequate  capacity  or  the  runs 
are  too  long,  the  upper  ends  will  receive  too  much  water  before 
the  water  reaches  the  lower  ends.     In  many  ways  the  manner 
of  preparation  for  the  use  of  water  will  affect  the  economy  of 
such  use. 

6.  Skill. — Closely  related  to  the  preparation  for  irrigation 
is  the  skill  with  which  the  existing  facilities  are  handled.     This 
will  vary  with  the  experience  of  the  farmer  or  of  the  help  he  may 
employ. 

7.  Care. — Even  with  adequate  facilities  and  skill,  the  water 
may  be  wasted  by  carelessness  if  the  necessity  of  care  be  not 
realized.     Where  water  is  abundant,  its  wasteful  use  is  universal. 
The  best  insurance  against  careless  handling  as  well  as  against 
poor  facilities  is  to  vary  the  water  charges  with  the  quantity  of 
water  used. 

8.  Cultivation. — If  the  surface  of  the  soil  is  kept  loosened 
to  a  considerable  depth,  and  the  fields  are  kept  clear  of  weeds 
which  would  consume  a  great  deal  of  water,  a  much  higher 
duty  of  water  can  be  attained  than  if  the  cultivation  of  the  soil 
is  neglected. 

It  will  be  noted  that  all  except  the  first  three  of  these  con- 
ditions depend  mainly  upon  the  individual  irrigator,  and  con- 
sequently cannot  be  predicted,  and  will  vary  with  different 
irrigators,  and  with  the  same  irrigator  as  he  improves  his  practice. 
The  duty  of  water  must,  moreover,  be  considered  in  two  stages: 

First,  the  "  net  duty,"  or  the  quantity  actually  used  on  the 
land. 

Second,  the  "  gross  duty,"  or  the  quantity  that  must  be 
diverted  from  the  stream,  or  stored  in  a  reservoir  in  order  that 
the  net  duty  may  be  fulfilled  at  the  land.  It,  therefore,  includes 
all  losses  from  evaporation  waste  and  seepage  to  which  the  water 
is  subject  before  it  reaches  the  farm. 

The  first  question  to  be  considered  is  the  quantity  of  water 
actually  needed  by  the  various  crops.  Elaborate  experiments 


U  TA II  EX  PERI  MEN  TS 


141 


under  various  conditions  of  soil,  crops  and  climate  have  been 
made  by  the  U.  S.  Department  of  Agriculture  and  the  various 
State  Experiment  Stations  on  this  subject. 

9.  Utah  Experiments. — The  following  table  shows  the  aver- 
age results  from  a  large  number  of  experiments  at  the  Utah 
Experiment  Station,  Logan,  Utah,  on  fine  sandy  loam: 

TABLE  XX.— ACREAGE  YIELD  OF  VARIOUS  CROPS  FOR  VARIOUS 
QUANTITIES  OF   IRRIGATION  WATER 


Inches 
of 
Water 

Wheat, 
Bu. 

Corn, 
Bu. 

Alfalfa, 
Lbs. 

Timothy, 
Lbs. 

Orchard- 
grass, 
Lbs. 

Oats, 
Bu. 

Potatoes, 
Bu. 

Sugar 
Beets, 
Tons 

5 

37-8 

9,2OO 

2,526 

62.3 

154 

13.8 

7    ^ 

41    <? 

70    I 

3,Q82 

182 

IO 

43-5 

89-5 

9,884 

2,829 

54-8 

195 

18.6 

15 

45-7 

93-9 

7,546 

3,844 

2:685 

71-5 

227 

19-5 

20 

91  .6 

9>°97 

80.7 

267 

21.3 

_- 

46   <c 

99    2 

9,12  ?A 

30 

48.0 

97-i 

8,840 

6,054 

244 

20.8 

40 

4,042 

79  -i 

250 

s° 

49-4 

96.0 

10,813 

24.  5 

60 

8,406 

^,27O 

3°4 

IOO 

2  214 

I    IQ2 

The  above  results  have  been  substantially  confirmed  by 
other  experiments,  showing  generally  some  increase  with  in- 
creasing amounts  of  water,  but  not  by  any  means  in  proportion 
to  the  water  used.  In  fact  as  will  be  seen  by  Table  XXI 
the  amount  of  product  per  unit  of  irrigation  water  decreases 
rapidly  as  the  amount  of  water  applied  increases.  These 
figures  are  obtained  by  reducing  the  results  of  the  same 
observations. 

The  application  of  more  water  above  a  moderate  amount 
not  only  gives  little  increase  in  yield  of  most  crops,  but  actually 
diminishes  some,  and  in  nearly  every  case  decreases  the  quality 
of  the  product.  In  all  crops  so  far  observed,  the  increase  of 
water  decreases  the  percentage  of  protein  or  nitrogenous  com- 
pounds, which  form  the  most  important  food  element.  The 
grains  are  made  softer,  and  tend  more  to  straw.  Alfalfa  and 


142 


DUTY  OF   WATER 


other  hay  crops  produce  a  greater  percentage  of  woody  material 
worthless  for  food  as  water  is  increased,  potatoes  and  beets 
are  made  more  watery  and  woody,  and  an  excess  of  water  upon 
cotton  is  distinctly  hurtful. 


TABLE  XXL— YIELDS  OF  VARIOUS  CROPS,  PER  ACRE-INCH  OF 
WATER  APPLIED,  FOR  VARIOUS  QUANTITIES  OF  IRRIGATION 
WATER 


Depth  of 
Water  in 
Inches 

Wheat, 
Bushels  per 
Acre-inch 

Corn, 
Bushels  per 
Acre-inch 

Potatoes, 
Bushels  per 
Acre-inch 

Sugar  Beets, 
Tons  per 
Acre-inch 

Alfalfa, 
Pounds 

Carrots. 
Tons 

5 

7.6 

31 

2.8 

7-5 

6.4 

6.1 

24 

2.  2 

IO 

4-3 

5-8 

20 

i.  9 

988 

15 

3-0 

4.6 

15 

i-3 

503 

1.6 

20 

3-6 

13 

i  .  i 

455 

25 

1.9 

3-2 

374 

0.9 

3° 

2-7 

8 

0.7 

2Q5 

40 

i-3 

6 

0.8 

50 

I  .0 

1.4 

0-5 

216 

60 

5 

0.6 

100 

.  .  . 

In  most  arid  districts  where  irrigation  is  possible,  the  area  of 
arable  land  is  far  in  excess  of  the  water  supply,  so  that  the  limit 
of  production  is  the  available  water,  and  the  economy  with 
which  this  is  used  has  a  profound  effect  upon  the  product,  as 
shown  by  Table  XXII,  showing  the  results  of  applying  a 
given  quantity  of  water  to  various  areas.  These  figures  are 
obtained  by  reduction  of  the  observations  at  the  Utah  Experi- 
ment Station,  given  above. 

As  irrigation  water  always  costs  something,  even  when  most 
abundant,  and  as  it  also  costs  something  to  apply  it,  it  is  always 
economical  to  apply  less  than  the  quantity  giving  the  maximum 
yield,  and  generally,  when  both  cost  and  value  of  results  are 
given  due  consideration  it  pays  to  stop  far  short  of  the 
maximum. 

The  natural  precipitation  available  for  plant  growth  includes 
not  only  that  which  falls  upon  the  growing  crops,  but  sudi 


AGRICULTURAL  DEPARTMENT  EXPERIMENTS 


143 


portion  of  the  winter  precipitation  as  is  retained  in  the  soil 
withm  the  zone  of  plant  root  feeding.  The  amount  thus  retained 
depends  partly  upon  the  natural  soil  and  climatic  conditions, 
and  partly  upon  the  efforts  which  are  made  through  cultivation 
to  facilitate  its  absorption  and  retard  evaporation. 


TABLE  XXII.— YIELDS  OF  DIFFERENT  CROPS  FROM  THE  APPLICA- 
TION OF  30  INCHES  OF  IRRIGATION  WATER  TO  VARIOUS 
ACREAGES 


i  Acre 

2  Acres 

3  Acres 

4  Acres 

6  Acres 

Wheat  (bushels)  
Corn  (bushels) 

48 
07 

91 

1  88 

130 

268 

166 

^16 

227 

Alfalfa  (pounds)  

8,840 

I  ^,OQ2 

2Q  6s  2 

r  r   2OO 

Timothy  (pounds)    

6  0^4. 

7  688 

i  ?  028 

Potatoes  (bushels) 

2  A.  A. 

AC  A 

rRcr 

j-o^y^0 
728 

Sugar  beets  (tons)  

20    8 

3Q     O 

sX  8 

82  8 

10.  Agricultural  Department  Experiments. — By  a  large  num- 
ber of  careful  measurements,  it  has  been  found  that  in  the 
Inter-Mountain  Region  with  about  8  inches  of  rain;  the  amount 
of  water  required  on  loam  soils  for  best  results  varied  from  i 
foot  to  3  feet  in  depth  c-n  the  land,  in  the  season,  the  average 
being  1.5  feet  for  grain  and  row  crops,  and  2.5  for  alfalfa.  Under 
normal  conditions  of  diversified  farming  an  average  of  2  feet 
in  depth  is  sufficient  for  the  crops,  but  an  allowance  of  10  to  20 
per  cent  should  be  made  for  waste  under  good  conditions, 
and  if  the  soil  be  very  sandy,  or  have  an  open  subsoil  within 
5  feet  of  the  surface,  it  will  be  difficult  to  avoid  large  losses 
into  the  subsoil,  and  allowance  for  this  must  be  made,  which 
may  run  very  high  in  some  cases,  unless  extreme  care  is  taken 
in  applying  the  water.  The  average  uses  on  the  Minidoka 
Project  in  Southern  Idaho,  having  a  wide  variation  in  soil 
conditions  varied  from  2.5  feet  for  loam  soils,  to  12  feet  for 
sand  with  gravelly  subsoils. 

The  following  table  is  the  result  condensed  from  a  number 
of  careful  observations: 


144  DUTY  OF  WATER 

TABLE   XXIII.— OPTIMUM  QUANTITIES  OF  WATER   FOR  VARIOUS 
CROPS,  ON  RETENTIVE   SOILS,   WITH   GOOD   CULTIVATION 


Max.  Yield 

Optimum 

Page 

Potatoes  (clay  loam)  
Potatoes  (sandy  loam)  
Sugar  beets  (fine  sandy  loam)  

26 

24  inches,  Bark 
24  inches,  Utah 
30  inches,  Utah 

47 
48 

Sugar  beets  (clay  loam)  

30  inches,  Utah 

From  measurements  on  more  than  100  farms  in  Southern 
Idaho,  in  1915  and  1916,  Bark  concluded  that  average  diversified 
farming  on  loam  soils,  required  an  average  monthly  application 
as  follows : 

April \      i  per  cent  of  total  application 

May          19 

June 28 

July 33 

August 17 

September  1-15   .     2  "  "  " 

Total 100 

The  percentage  required  in  April  and  September  would  be 
greater  in  a  warmer  climate  with  longer  season,  which  would, 
of  course,  diminish  the  percentage  in  other  months. 

ii.  In  the  U.  S.  Reclamation  Service  it  has  been  the  general 
practice  to  measure  the  water  used  in  irrigation,  and  the  exten- 
sion act  passed  in  1914  requires  maintenance  charges  to  be 
fixed  according  to  the  amount  of  water  used,  a  practice  pre- 
viously followed  on  a  few  of  the  projects.  As  a  result,  we  have 
a  good  deal  of  accurate  data  on  water  duty  upon  those  projects. 
Some  of  these  data  are  condensed  in  Table  XXIV. 

Familiarity  with  local  conditions  lends  increased  interest 
to  the  above  table.  The  first  important  condition  is  the  length 
of  season,  the  projects  in  Southern  Arizona  having  a  season 
of  365  days,  while  all  the  rest  have  shorter  seasons.  Notwith- 
standing this  fact  and  the  further  fact  that  they  receive  less 
than  8  inches  of  rainfall,  the  total  quantity  of  water  applied 
per  acre  is  less  than  upon  many  of  the  projects  of  shorter  season 


AGRICULTURAL  DEPARTMENT  EXPERIMENTS 


145 


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146 


DUTY  OF   WATER 


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AGRICULTURAL  DEPARTMENT  EXPERIMENTS  147 

and  greater  rainfall.  At  Yuma,  however,  a  high  ground  water 
table  assists  in  keeping  down  the  quantity  of  water  needed. 
Altogether,  without  much  question,  considering  all  conditions, 
Salt  River  Valley  shows  the  best  practice  in  water  economy 
of  any  of  the  projects.  This  is  due  to  the  evenness  of  surface 
and  slope,  to  an  excellent  system  of  rotation,  and  to  frequent 
cultivation,  the  outgrowth  of  the  high  value  of  water  and  ex- 
perience in  its  use. 

The  best  practice  of  any  Northern  project  on  the  list  is 
on  the  Huntley,  although  the  high  duty  there  is  partly  due  to 
favorable  climate  and  soil.  The  most  wasteful  practice  is  upon 
the  Rio  Grande  project,  where  with  shorter  season,  and  some- 
what greater  rainfall,  more  than  twice  as  much  water  is  applied 
as  at  Salt  River.  This  is  the  less  excusable  as  most  of  the 
Rio  Grande  Valley  has  a  high  water  table,  and  some  is  actually 
water-logged;  nor  is  there  any  very  open  soil,  requiring  much 
water.  The  main  explanation  is  the  community  operation  of 
laterals  in  which  no  control  is  exercised  over  the  amount  of 
water  used,  and  the  primitive  methods  of  irrigation.  It 
is  fast  ruining  the  land,  and  strenuous  efforts  are  being  made 
by  the  leading  men  to  induce  the  small  communities  to  surrender 
the  canals  to  the  Government,  and  to  establish  rigid  control  and 
severe  penalties  against  water  waste. 

Next  in  order  of  reckless  waste  is  the  Uncompahgre  project, 
which  uses  in  seven  months  more  than  twice  as  much  water  as 
Salt  River  does  in  twelve.  Although  the  valley  has  a  steep  slope 
and  good  natural  surface  drainage,  the  excessive  application  of 
water  has  water-logged  considerable  areas  of  land,  and  this 
area  is  increasing.  The  sale  of  water  by  the  second-foot  instead 
of  by  the  acre-foot  is  one  of  the  leading  causes,  as  it  offers  no 
inducement  to  economy  except  at  the  peak  of  the  season.  This 
practice  is  the  outgrowth  of  local  habit,  and  efforts  are  being 
made  to  change  it. 

Excessive  quantities  of  water  are  also  used  on  the  Umatilla 
Project,  but  this  is  due  to  open  sandy  soil  with  very  coarse  sub- 
soil, through  which  the  water  readily  sinks  beyond  the  reach 
of  crop  roots,  and  frequent  irrigation  is  required.  The  same  is 


148 


DUTY  OF   WATER 


true  on  a  large  part  of  the  Minidoka  and  Orland  projects,  and 
on  parts  of  the  Boise  and  Truckee-Carson  Projects.  The  Sun 
River,  Milk  River,  Lower  Yellowstone,  Belle  Fourche  and 
Klamath  Projects  are  in  semi-arid  regions,  receiving  the  major 
portion  of  their  rainfall  in  the  growing  season,  and  crops  are 
often  raised  without  irrigation.  They  therefore  use  only  small 
quantities  of  irrigation  water. 

12.  A  Committee  on  Irrigation  from  the  American  Society  of 
Agricultural  Engineers  addressed  a  questionnaire  to  several 
hundred  leading  men  concerned  directly  or  indirectly  with 
irrigation,  whose  opinions  on  the  subject  were  deemed  important. 
The  replies  concerning  the  duty  of  water  are  condensed  in  the 
following  table: 

TABLE  XXVI.— AMOUNT   OF  WATER   USED   ANNUALLY 


CEREAI 

CROPS 

FORAGE 

CROPS 

Class  of  Soil 

Depth 

Acres  per 
Second-foot 

Depth 

Acres  per 
Second-foot 

Light  

2  .  I 

I  ^ 

3  •  I 

80 

IVIedium 

I    n 

187 

2     Z 

75 

Heavy  

I  .  2 

242 

2.  I 

I05 

Average 

I    7 

IQ^ 

2    6 

87 

Independently  of  careful  scientific  observations,  are  numer- 
ous community  experiences  which  throw  valuable  light  on  the 
duty  of  water  in  a  large  community  in  a  long  series  of  years. 
On  this  point  Fortier  says :  * 

"  Some  twenty- five  years  ago  the  irrigators  of  the  Greeley  district  in  Northern 
Colorado  were  using  a  second-foot  of  water  on  40  to  50  acres.  In  recent  years 
the  same  quantity  has  served  fully  three  times  as  much  land  with  far  better  results 
when  measured  in  crop  yields.  Again,  in  the  early  nineties,  the  farmers  in  the 
Bear  River  Valley  in  Northern  Utah  used  a  second-foot  on  60  to  80  acres,  but 
during  the  past  few  years  the  average  duty  has  been  a  second-foot  for  120  acres. 
Furthermore,  when  the  Legislative  Assembly  of  Wyoming  in  1891  limited  the 
duty  throughout  the  State  to  one  second-foot  for  each  70  acres,  it  was  actuated 
by  the  best  of  motives.  Such  a  duty  was  then  high.  Now  it  is  too  low  and  the 
State  is  handicapped  by  having  apportioned  so  large  a  volume  of  its  public  waters 
on  the  limit  fixed  by  statute." 

*  Use  of  Water  in  Irrigation,  page  135. 


AGRICULTURAL  DEPARTMENT  EXPERIMENTS  149 

In  a  decision  by  the  Supreme  Court  of  Arizona  in  1910,  the 
duty  of  water  for  Salt  River  Valley  was  fixed  at  48  miner's 
inches,  or  1.2  second-feet,  for  each  quarter  section  of  land.  This 
is  equivalent  to  133!  acres  to  the  second-foot.  It  should  be 
noted  that  this  use  is  in  a  very  hot  and  very  dry  climate,  where 
for  months  at  a  time  no  rainfall  appears  to  assist  in 
moistening  the  crops,  the  mean  annual  rainfall  being  about 
8  inches. 

This  rule  limiting  water  usage  has  been  in  force  for  about 
seven  years,  and  has  aroused  no  complaint  of  shortage,  as  experi- 
ence shows  this  quantity  to  be  ample  even  for  those  crops  of 
greatest  requirement,  and  on  sandy  soil.  In  fact  the  records 
of  water,  delivery  show  an  average  use  throughout  the  year 
only  about  3  feet  in  depth  on  the  land  actually  irrigated,  although 
the  irrigation  season  is  twelve  months  in  length. 

This  is  only  about  one-half  the  full  use  of  the  above  allow- 
ance as  an  average,  so  that  it  is  evident  that  this  full  use  is 
invoked  only  in  mid-summer,  and  that  the  demand  is  reduced 
to  an  average  of  about  one-half  in  spring  and  autumn,  and  one- 
fourth  in  winter.  The  marked  improvement  over  the  water 
duty  of  other  regions,  and  of  the  same  valley  in  former  years, 
is  due  to  the  increased  value  of  water,  and  a  charge  in  pro- 
portion to  quantity  used,  leading  to  more  careful  and  more 
skillful  use.  The  leading  practices  developed  by  this  condition 
are: 

1.  An  efficient  system  of  rotation,  delivering  only  a  day  in 
eight,  and  use  of  large  heads. 

2.  Careful  preparation  of  the  land. 

3.  Re-use  of  waste  water  for  irrigation,  by  picking  it  up  at 
lower  end  of  the  field. 

4.  Cultivation  of  the  land  soon  after  each  irrigation. 

Even  with  these  practices  considerable  areas  in  Salt  River 
Valley  have  become  waterlogged,  and  these  areas  are  growing. 

Of  course  there  remains  much  room  for  improvement  in  these 
and  similar  practices,  so  that  the  high  duty  of  water  can  be 
made  practicably  much  higher.  This  will  undoubtedly  be 
done  as  the  value  of  water  advances. 


150  DUTY  OF  WATER 

That  such  a  hope  is  well  founded  is  demonstrated  by 
irrigation  practices  in  Southern  California,  where  nearly  double 
this  duty  is  obtained,  by  more  thorough  employment  of  the 
above  precautions  and  by  the  use  of  pipes  and  lined  canals, 
cement  head  ditches  and  other  devices  for  saving  water.  Per- 
haps the  most  important  measure  that  has  led  to  such  a  high 
duty  and  such  successful  results  from  irrigation  in  Southern 
California  is  the  habit  of  thorough  cultivation  of  the  surface 
as  soon  as  possible  after  each  irrigation  and  each  heavy  shower 
of  rain.  This  provides  a  soil  mulch  which  conserves  the  mois- 
ture and  also  destroys  all  weeds  which  has  the  same  tendency. 
The  results  obtained  in  Arizona  are  easily  reached  in  any  region 
by  the  adoption  of  the  simple  measures  enumerated,  which  are 
good  in  themselves,  and  should  be  applied  nearly  everywhere. 
The  results  in  Southern  California  furnish  the  goal  towards 
which  Arizona  and  all  the  rest  should  strive. 

The  Utah  Agricultural  College  has  done  much  useful  work 
in  teaching  and  spreading  information  in  favor  of  greater  care 
in  the  use  of  water.  In  conjunction  with  the  State  Conserva- 
tion Commission  it  has  widely  promulgated  the  following 
twelve  rules  for  the  use  of  irrigation  water: 

1.  Store  the  Rainfall  in  the  Soil. — Deep,  thorough  plowing 
enables  the  soil  to  absorb  and  retain  most  of  the  rain  and  snow 
water.    The  more  rainfall  is  stored  in  the  soil  the  less  irrigation 
water  will  be  needed. 

2.  Cultivate    Frequently    and    Thoroughly. — Water    is    easily 
lost  from  soils  by  evaporation.     Stirring  the  top  soil  reduces 
this   evaporation.     The   soil   should   be   thoroughly   cultivated 
early  in  the  spring,  as  soon  as  possible  after  irrigation,  and 
usually  once  or  more  between  irrigation.     Thorough  cultivation 
will  reduce  the  water  needed  in  irrigation. 

3.  Keep  the  Soil  Fertile. — The  more  fertile  a  soil  is,  the  less 
water  is  needed  to  produce  a  pound  or  ton  of  the  crop.     Plow 
deeply,  cultivate  thoroughly,  use  barnyard  manure,  and  less 
irrigation  water  will  be  needed. 

4.  Plant    in    Well-moistened   Soil. — Well-moistened    soil    at 
planting  time  permits  better  root  development,  and  delays  the 


AGRICULTURAL  DEPARTMENT  EXPERIMENTS  151 

time  of  the  first  irrigation,  and  thus  saves  irrigation  water 
during  the  summer.  If  rains  and  snow  do  not  moisten  soils 
sufficiently  for  planting,  irrigate  in  fall,  or  in  early  spring, 
before  planting. 

5.  Don't    Irrigate   too   Early. — By    postponing    as    long   as 
possible  the  first  irrigation  after  planting,  a  better  root  develop- 
ment is  secured  and  less  irrigation  water  is  needed  to  produce 
the  crop. 

6.  Irrigate  by  the  Correct  Method. — Where  water  is  plentiful, 
the  flooding  method  may  be  used;    where  water  is  scarce,  the 
furrow   method   only   should   be   employed.     Lead   the   waste 
water  from  the  furrows  to  other  fields. 

7.  Irrigate  at  the  Proper  Time. — Withhold  water  until  the 
crop  is  in  real  need.     When  irrigating,   apply  enough  water 
to  supply  the  crop  for  at  least  ten  days.     Irrigate  thoroughly 
when  potatoes  are  in  bloom;   corn  in  tassel  or  silk;   lucern  just 
beginning  to  bud,  and  grains  forming  seed. 

8.  Use   Water   in   Moderation. — The   acre   yield   of   a   crop 
increases  as  more  water  is  used,  up  to  a  certain  limit,  beyond 
which  more  water  causes  a  decrease  in  the  yield. 

9.  Spread  the  Water  over  Larger  Areas. — The  yield  of  crop 
per  unit  of  water  always  becomes  smaller  as  more  water  is 
added.     The  less  water  is  used  in  irrigation,  the  more  crop  is 
obtained  for  the  water  used.     In  Utah  land  is  plentiful,  water 
is  scarce;    it  is  more  important  to  get  a  large  crop  for  each 
acre-foot  of  water  than  for  each  acre  of  land. 

10.  Kill  the  Weeds. — Weeds  use  as  much  water  as  do  many 
profitable   crops.     It   costs  usually   2000  pounds  of  water   to 
produce  i  pound  of  weeds.     Killing  the  weeds  will  leave  more 
water  for  our  crops. 

11.  Repair  the  Leaky  Ditches. — Tremendous   quantities  of 
water  seep  from  most  of  our  canals  and  ditches.     Stop  the 
leaky  places.     It  will  often   pay  to   cement  the  whole  canal. 

12.  Measure  the  Water. — Land  is  measured  carefully,  but 
water,  more  valuable  than  land,  is  seldom  measured.     Great 
progress  will  be  made  by  Utah  as  soon  as  farmers  faithfully 
measure  and  keep  an  account  of  the  water  used  on  the  land, 


152  DUTY  OF  WATER 

This  is  one  of  Utah's  greatest  irrigation  needs.     The  Cippoletti 
Weir  may  be  used  by  any  farmer  for  the  measurement  of  water. 

REFERENCES  FOR  CHAPTER  X 

WIDTSOE,   JOHN  A.     Principles   of   Irrigation   Practice.     Macmillan   Company, 

New  York. 
BROWN,  HANBURG. — Irrigation,  Its  Principles  and  Practice.     D.  Van  Nostrand 

Co.,  New  York. 
FORTIER,   SAMUEL.     Use  of  Irrigation  Water.     McGraw-Hill   Book   Company, 

New  York. 
CARPENTER,  L.  G.     Duty  of  Water.     Bulletin  No.  22,  State  Agricultural  College, 

Ft.  Collins,  Colorado. 
MEAD,  ELWOOD,  and  Others.     Use  and  Duty  of  Water  in  Irrigation.     Bulletin 

No.  86,  U.  S.  Office  of  Experiment  Stations. 
U.  S.  Reclamation  Service.     Sixteenth  Annual  Report. 
WILSON,  H.  M.     American  Irrigation  Engineering,  Part  II,  i3th  Annual  Report, 

U.  S.  Geological  Survey. 
MEAD,  ELWOOD.     Report  on  Irrigation  on  Investigations  for  1904.     Bulletin  No. 

158,  U.  S.  Office  of  Experiment  Stations. 
TEELE,  R.  P.    Review  of  Ten  Years  of  Irrigation  Investigations.     Annual  Report 

of  U.  S.  Office  of  Experiment  Stations  for  1908. 
NEWELL,  F.  H.     Annual  Reports  on  Operation  and  Maintenance  of  Reclamation 

Projects,  1910-11-12-13,  U.  S.  Reclamation  Service. 
BARK,  DON  H.     Duty  of  Water  Investigations  in  Idaho.     Parts  of  8th  and  gth 

Biennial  Reports  of  State  Engineer  of  Idaho,  for  1910-11-12. 
Inquiry  of  Am.  Soc.  of  Agricultural  Engineers.     Reclamation  Record,  April,  1918. 


CHAPTER  XI 
MEASUREMENT  OF  IRRIGATION  WATER 

WATER  measurements  in  connection  with  an  irrigation 
system  are  of  two  main  classes. 

First  are  those  measurements  of  the  stream  and  of  the  main 
canal  and  larger  laterals  which  are  of  use  in  the  operation  of 
the  system,  and  do  not  bear  directly  upon  the  amount  of  water 
delivered  to  the  individual  irrigator.  The  streams  or  canals 
measured  are  of  considerable  size  and  the  methods  employed 
in  measurement  are  similar  to  those  used  in  gaging  rivers. 

The  second  class  of  measurements  are  those  designed  to 
indicate  the  amount  of  water  delivered  to  each  irrigator.  They 
are  of  relatively  small  amounts,  and  to  obtain  the  necessary 
degree  of  precision,  require  the  use  of  other  means  than  those 
usually  employed  on  large  streams. 

i.  Gaging  Streams. — The  first  step  in  the  study  of  the 
water  supply  should  be  the  establishment  of  systematic' observa- 
tions of  stream  flow  at  the  various  points  where  such  data  are 
required,  and  records  of  the  daily  flow  should  be  kept.  A  gage 
should  be  provided  by  which  to  observe  the  height  of  the  sur- 
face of  the  water  in  the  river  and  should  be  observed  daily  or 
oftener  so  as  to  obtain  correct  results  of  the  daily  mean.  The 
simplest  form  of  gage  is  a  wooden  rod-,  graduated  in  feet  and 
tenths  so  as  to  be  easily  read,  with  the  graduation  made  per- 
manent with  nails  or  otherwise,  so  that  the  action  of  the  water 
will  not  obliterate  them.  A  position  should  be  selected  for  the 
gage  rod  where  it  will  be  protected  from  driftwood,  and  yet  be 
easily  read,  and  show  the  true  height  of  the  water  in  the  river. 
If  no  better  plan  presents  itself,  the  rod  may  be  laid  on  the 
ground  sloping  up  from  the  river,  and  fastened  firmly  to  stakes 
or  posts.  The  graduations  may  then  be  located  on  it  by  means 

153 


154  MEASUREMENT  OF  IRRIGATION  WATER 

of  a  Y  level.  Such  a  gage  may  be  read  twice  a  day,  and  this 
will  give  fair  results  on  most  streams. 

Somewhat  more  reliable  results  may  be  obtained  by  pro- 
viding a  well  near  the  river  above  high  water,  the  bottom  of 
which  extends  somewhat  below  low  water,  and  connecting  the 
bottom  of  the  well  with  the  river  by  a  horizontal  pipe,  so  that 
the  water  in  the  well  will  always  stand  at  the  level  of  the  water 
in  the  river.  By  this  arrangement  difficulty  with  driftwood  is 
avoided,  and  observations  may  be  accurately  taken  with  a  hook 
gage.  If  greater  accuracy  is  desirable,  or  if  the  river  is  subject 
to  sudden  fluctuation,  it  may  be  advisable  to  install  a 
mechanical  self-recording  gage,  of  which  several  are  on  the 
market.  They  require  frequent  attention  to  keep  them  in  order, 
but  by  making  continuous  record  give  much  greater  accuracy 
on  a  fluctuating  stream  than  periodic  observations  of  a  gage. 
Measurements  of  the  actual  discharge  of  the  stream  should  be 
made  at  frequent  intervals,  depending  upon  the  character  of 
the  stream  bed.  If  this  is  of  permanent  character,  a  complete 
series  of  measurements  taken  at  high,  low,  and  intermediate 
stages  will  serve  to  establish  approximate  values  for  the  various 
gage  heights,  and  permit  the  construction  of  a  curve  of  discharge; 
and  thereafter  measurements  need  be  made  only  sufficient  to 
check  the  stability  of  the  cross-section  and  to  confirm  the 
stability  and  reliability  of  the  gage.  There  are  few  river  chan- 
nels, however,  except  those  in  solid  rock,  that  are  naturally  so 
stable  that  they  do  not  undergo  material  modification  in  times 
of  flood,  so  that  in  practice  it  is  usually  necessary  to  take  a 
series  of  measurements  every  year.  Especially  is  it  important 
to  secure  measurements  of  extreme  high  and  low  water,  so  as 
to  control  the  extremities  of  the  curve  of  discharge. 

The  discharge  of  the  stream  should  be  measured  in  the 
vicinity  of  the  gage,  so  that  no  appreciable  gain  or  loss  can  occur 
between. 

The  depth  may  be  measured  by  a  rod  or  sounding  line  at 
measured  intervals  across  the  stream,  each  sounding  represent- 
ing half  the  distance  to  the  next  sounding  adjacent  on  each 
side.  The  frequency  of  the  soundings  should  depend  upon 


GAGING  STREAMS  155 

the  roughness  of  the  channel,  a  few  soundings  being  sufficient 
where  the  stream  is  of  nearly  uniform  depth,  and  only  roughly 
approximate  results  are  required.  For  convenience,  the  sound- 
ings may  be  made  equidistant,  and  each  sounding  should  be 
multiplied  by  the  width  of  the  section  which  it  represents. 
This  will  give  the  area  of  that  cross-section,  and  the  sum  of  all 
these  cross-sections  will  give  the  cross-section  of  the  stream, 
and  this  multiplied  by  the  mean  velocity  of  the  water  will  give 
the  total  discharge 

A  rough  preliminary  measurement  of  velocity  may  be  made 
by  surface  floats,  timing  their  passage  over  a  measured  course. 
The  mean  velocity  will  be  about  nine-tenths  of  the  average 
surface  velocity  in  ordinary  streams  with  smooth  bottoms  and 


FIG.  48.— Haskell  Current  Meter. 

somewhat  less,  for  rough  gravelly  sections.  A  convenient  form 
of  surface  float  is  a  tall  bottle,  with  just  enough  water  in  it  to 
make  it  float  upright,  and  a  white  rag  attached  to  the  cork  to 
make  it  conspicuous.  Several  such  floats  should  be  passed 
over  the  course  at  different  parts  of  the  stream  and  the  time 
carefully  taken.  A  straight  course  should  be  selected  free  from 
eddies  or  material  changes  in  section.  More,  reliable  and 
accurate  measurements  of  velocity  may  be  made  with  a  current 
meter,  of  which  several  efficient  types  are  obtainable.  Those 
most  used  are  the  Price  meter,  Fig.  49,  and  the  Haskell  meter, 
Fig.  48. 

The  Haskell  meter  has  a  slight  advantage  in  responding 
only  to  the  component  of  water  motion  parallel  to  the  axis  of 


156 


MEASUREMENT  OF  IRRIGATION   WATER 


: 


FIG.  49. — Price  Electric  and  Acoustic  Current  Meters. 


GAGING  STREAMS  157 

the  meter,  but  will  not  register  velocities  as  low  nor  as  high  as 
the  Price  meter,  and  if  the  shaft  on  which  it  revolves  becomes 
slightly  roughened  by  rust,  or  otherwise,  it  seriously  affects  the 
coefficient  of  friction,  and  hence  the  rating  of  the  meter. 

The  electric  meter  which  has  been  found  to  work  most 
satisfactorily  under  nearly  all  the  varying  conditions  of  depth 
and  velocity  by  the  hydrographers  of  the  U.  S.  Geological  Survey 
and  U.  S.  Engineer  Corps  is  the  small  Price  electric-current 
meter  (Fig.  49).  It  is  accurate  for  streams  of  nearly  any  velocity, 
and  is  practically  standard  with  both  organizations.  Each 
revolution  of  the  wheel  is  indicated  by  a  sounder,  consisting 
of  a  telephone  receiver  excited  by  a  small  battery  cell.  Two 
small  insulated  wires,  attached  to  the  stem  and  to  the  contact 
spring  in  the  head,  are  connected  with  the  sounder  through  the 
suspending  cable. 

The  Price  acoustic  current  meter  is  a  modification  of  the 
Price  electric  meter.  It  is  especially  desirable  for  its  portability 
and  ease  of  handling  as  it  weighs  but  little  over  a  pound.  In 
very  shallow  streams  it  gives  the  most  accurate  results  of  any 
meter,  and  is  held  at  the  proper  depth  by  a  metal  rod  in  the 
hands  of  the  observer.  It  is  designed  especially  to  stand  hard 
knocks  which  may  be  received  in  turbid  irrigation  waters,  and 
can  be  used  in  high  velocities,  as  only  each  tenth  revolution 
is  counted.  Its  head,  like  that  of  the  electric  meter,  consists 
(Fig.  49) ,  of  a  strong  wheel  composed  of  six  conical-shaped  cups, 
which  revolve  in  a  horizontal  plane;  its  bearings  run  in  two 
cups  holding  air  and  oil  in  such  manner  as  entirely  to  exclude 
water  or  gritty  matter.  Above  the  upper  bearing  is  a  small 
air-chamber,  into  which  the  shaft  of  the  wheel  extends.  The 
water  cannot  rise  into  this  air-chamber,  and  in  it  is  a  small 
worm-gear  on  the  shaft,  turning  a  wheel  with  twenty  teeth. 
This  wheel  carries  a  pin  which  at  every  tenth  revolution  of  the 
shaft  trips  a  small  hammer  against  the  diaphragm  forming  the 
top  of  the  air-chamber,  and  the  sound  produced  by  the  striking 
hammer  is  transmitted  by  the  hollow  plunger-rod  through  a 
connecting  rubber  tube  to  the  ear  of  the  observer  by  an  ear- 
piece. The  plunger-rod  is  in  2-foot  lengths,  and  is  graduated  to 


158  MEASUREMENT  OF  IRRIGATION  WATER 

feet  and  tenths  of  feet,  thus  rendering  it  serviceable  as  a  sound- 
ing or  gaging  rod. 

2.  Use  of  the  Current  Meter. — A  bridge  spanning  a  stream 
without  piers  in  the  channel  is  the  most  convenient  provision 
for  using  a  current  meter.  Even  one  or  two  piers  in  the  stream 
may  be  tolerated  if  they  are  not  clogged  with  drift,  and  do  not 
greatly  interfere  with  the  smooth  flow  of  the  water.  If  the 
stream  is  sufficiently  shallow,  a  resort  to  wading  may  be  practi- 
cable at  time  of  low  water,  but  obviously  will  not  do  at  high 
water,  nor  at  any  time  when  the  velocity  is  high,  as  the  body 
of  the  observer  will  cause  eddies  and  vitiate  the  results. 

In  the  absence  of  a  bridge  without  piers  in  the  stream,  the 
best  provision  for  gaging  is  to  stretch  a  cable  across  the  stream, 
and  from  this  suspend  a  small  car  in  which  the  observer  can 
ride,  propelling  the  car  by  pulling  on  the  cable,  and  stopping 
at  certain  points  indicated  by  a  tagged  wire  parallel  to  the  cable. 
The  diagram,  Fig.  52,  shows  such  a  station.  In  the  absence  of 
the  car  a  boat  may  be  used,  anchored  to  the  cable,  but  this 
somewhat  interferes  with  the  current,  and  is  apt  to  swing  about 
during  the  observation  and  impair  its  accuracy. 

In  lowering  a  current  meter  into  a  deep  stream  in  time  of 
flood,  the  strong  current  tends  to  carry  it  downstream,  and  to 
prevent  its  reaching  the  bottom  or  any  considerable  depth. 
To  remedy  this  tendency,  a  heavy  wire  may  be  stretched  across 
the  river  50  or  100  feet  above  the  gaging  section,  and  upon  this 
wire  a  small  pulley  is  carried  from  which  a  smaller  wire  extends 
to  the  meter  line,  to  which  it  is  attached  just  above  the  meter 
and  prevents  its  deflection  downstream. 

A  flowing  stream  has  a  sloping  surface,  and  moves  under  the 
action  of  gravity,  retarded  by  friction  on  the  bottom,  the  banks, 
and  in  a  small  degree  on  the  air.  The  lowest  velocity  is  at 
and  near  the  bottom  and  sides  on  account  of  their  retarding 
effect.  The  maximum  velocity  is  just  below  the  surface,  in 
the  central  portion  of  the  channel,  unless  a  deeper  part  exists, 
in  which  case  the  depth  may  vary  that  law.  In  order  to  find 
the  mean  velocity  of  the  water  in  any  vertical  line,  several 
methods  are  in  use. 


USE  OF   THE  CURRENT  METER  159 

1.  The   integration    method    is    the    moving   of    the  -meter 
slowly  and  regularly  from  surface  to  bottom,  and  to  surface 
again.     This  must  be  done  so  slowly  that  the  vertical  motion 
of  the  meter  will  be  an  insignificant  fraction  of  the  horizontal 
motion  of  the  water,  otherwise  the  correctness  of  the  record 
may  be  affected  especially  with  the  cup  type  of  meter  such  as 
the  Price  meter. 

2.  The  measurement  of  velocity  at  six-tenths  of  the  depth, 
has  been   found   to   generally  give  results   approximating   the 
mean  velocity  of  the  vertical  line  passing  through  the  point 
measured. 

3.  In  deep  streams  the  mean  of  measurements  of  velocity  at 
surface,  mid-depth  and  bottom  will  give  a  close  approximation 
to  the  mean  velocity. 

Good  results  from  current  meter  measurements  cannot  be 
obtained  except  at  reaches  where  the  channel  is  fairly  straight 
and  regular,  and  practically  free  from  whirlpools,  eddies  and 
back  currents. 

An  overflow  dam  or  weir  furnishes  an  excellent  opportunity 
for  measuring  the  discharge  of  a  stream,  if  it  is  fairly  smooth 
and  regular  along  its  crest.  If  it  has  a  large  bay  of  nearly 
quiet  water  back  of  it,  the  discharge  may  be  computed  by  one 
or  other  of  the  empirical  formulae,  by  measuring  the  height  of 
the  water  above  the  crest  of  the  weir  at  a  point  above  the  line 
of  accelerated  velocity,  where  the  measurement  gives  the  general 
height  of  the  still  bay. 

If  the  pond  above  the  dam  has  been  filled  with  sediment,  the 
various  weir  formulae  are  not  applicable,  but  the  weir  may  be 
calibrated  by  measuring  the  stream  with  a  current  meter  a 
short  distance  above  or  below  the  weir,  and  when  once  this  is 
well  done,  for  all  stages  from  extreme  low  water  to  extreme 
flood  stage,  the  stability  of  the  weir,  if  it  be  of  masonry,  insures 
accurate  results  as  long  as  no  change  occurs  in  the  shape  or 
elevation  of  the  weir  crest. 

Where  the  section  measured  is  sandy  and  constantly  shifting, 
the  gage  readings  cannot  be  depended  upon  as  indications  of 
discharge  unless  checked  frequently  by  actual  complete  discharge 


160 


MEASUREMENT  OF  IRRIGATION  WATER 


USE  OF  THE  CURRENT  METER 


161 


*•-' 

u' 


FIG.  51. — Cable  Gaging  Station,  with  Automatic  Continuous  Recording  Gage. 


FIG.  52. — Cable  and  Car  Gaging  Station. 


162 


MEASUREMENT  OF  IRRIGATION  WATER 


measurements.     Such  streams  are  the  Colorado,  Rio  Grande, 
Arkansas  and  Platte  after  they  leave  the  mountains. 

These  streams  scour  their  channels  at  time  of  high  water 
and  fill  them  again  at  low  stages,  and  at  all  times  are  building 
bars  or  cutting  banks,  and  their  channels  are  thus  constantly 
shifting,  so  that  unless  a  fixed  weir  can  be  used,  it  is  necessary 
in  order  to  get  accurate  results  to  make  very  frequent  measure- 
ments, ranging  from  daily  in  times  of  high  water,  to  semi- 


.  53.— Wire  and  Boat  Gaging  Station. 


weekly  or  weekly  at  low  stages.  Even  these  results  are  not  as 
accurate  as  less  frequent  measurements  on  streams  with  gravel 
channels. 

Where  the  channel  is  of  coarse  gravel  or  bowlders  and  hence 
relatively  stable,  the  principal  changes  occur  at  times  of  flood 
and  a  measurement  or  two  at  or  near  the  peak  of  the  flood 
and  at  extreme  low  water,  with  a  few  at  intermediate  stages, 


USE  OF   THE  CURRENT  METER  163 

generally  give  a  good  rating  curve  to  serve  till  the  next  -flood 
stage.  The  rating  curve  at  such  places  is  often  very  stable, 
but  should  be  checked  carefully  at  and  after  each  flood  stage. 

Streams  through  clay  regions  are  apt  to  be  more  shifting  than 
those  with  gravel  sections,  but  are  generally  susceptible  of  fair 
determination  by  the  methods  just  described,  with  somewhat 
more  frequent  measurements.  No  section  is  entirely  free  from 
change  unless  of  rock,  or  of  concrete  or  other  artificial  con- 
struction. 

In  cold  countries  like  the  Northern  United  States  and 
Canada  special  problems  and  considerable  difficulty  are  pre- 
sented in  measuring  frozen  streams.  In  the  early  winter 
needle  and  anchor  ice  are  apt  to  form  in  rapids  and  flow  in 
masses,  sometimes  even  clogging  the  stream  where  frozen  over, 
and  causing  back  water.  The  surface  of  the  stream  may  freeze 
at  the  edges,  leaving  the  center  of  the  channel  open,  thus  com- 
plicating the  work  of  measurement. 

After  the  channel  freezes  over  the  discharge  measurements 
are  made  through  holes  in  the  ice,  large  enough  to  allow  the 
current  meter  to  pass  through  freely.  The  depth  of  the  stream 
is  taken  as  the  distance  from  the  bottom  of  the  ice  to  the  bottom 
of  the  stream.  The  velocity  is  taken  by  the  vertical  velocity- 
curve  method,  which  as  adapted  to  winter  use,  may  be  described 
as  follows: 

The  meter  is  held  just  below  the  lower  surface  of  the  ice, 
and  the  velocity  at  that  point  recorded.  This  is  repeated  at 
different  depths  throughout  the  vertical.  These  results  are 
plotted  with  velocities  in  feet  per  second  as  abscissae,  and  their 
corresponding  depths  in  feet  as  ordinates,  and  a  curve  is  drawn 
through  the  points.  The  mean  velocity  is  obtained  by  dividing 
the  area  included  between  the  curve  and  its  axis,  by  the  depth. 
This  may  be  measured  by  planimeter,  or  estimated  by  squares. 
A  close  approximation  may  be  more  easily  obtained  by  dividing 
the  depth  into  a  number  of  equal  parts,  taking  corresponding 
velocities  from  the  curve  and  averaging  these.  The  mean 
velocity  multiplied  by  the  depth  as  measured  will  give  the 
discharge. 


164  MEASUREMENT  OF  IRRIGATION   WATER 

3.  Hydraulic  Formulae.  In  1775,  Chezy,  a  French  engineer, 
developed  a  formula  for  computing  the  flow  of  water  in  conduits, 
either  open  or  closed. 


Where  F  =  the  mean  velocity  of  the  water; 

R  =  The  hydraulic  radius  of  the  stream  obtained  by  divid- 

ing the  area  of  cross-section  of  the  stream  by  the 

wetted  perimeter; 

5  =  the  tangent  of  the  angle  of  slope; 
C  =  a  coefficient  then  supposed  to  be  constant,  but  now 

known    to   vary   with   several   factors,    especially 

the  friction  of  the  channel. 

The  researches  of  Ganguillet  and  Kutter  produced  important 
modifications  of  the  above  formula,  in  which  the  factor  C  is 
replaced  by  an  expression  which  takes  into  account  the  roughness 
of  the  channel,  and  certain  functions  of  the  slope  and  the 
hydraulic  radius.  The  friction  is  represented  by  the  variable 
"  «."  This  formula,  which  is  in  general  use  for  open  conduits, 
and  also  to  some  extent  for  closed  conduits,  is  expressed  thus: 


1.81  .0028 

— h4i.6+- 


v. 


rs. 


The  value  of  the  factor  "  n  "  is  empirical  and  must  be 
assumed  largely  upon  judgment,  owing  to  the  difficulty  of 
defining  with  accuracy  the  multitude  of  details  which  effect  the 
retarding  influence  of  the  channel. 

4.  Measurement  of  Water  to  the  User. — The  accurate 
measurement  of  water  to  each  irrigator  is  a  prime  necessity  of 
every  irrigation  system.  Where  the  water  supply  is  limited, 
and  the  area  of  irrigation  is  thereby  limited,  as  is  generally  the 
case,  it  is  important  that  the  most  economical  use  of  water  be 
secured,  in  order  that  the  largest  area  may  be  irrigated  and  the 
greatest  production  thereby  secured.  It  is  still  more  important 


MEASUREMENT  OF  WATER   TO   THE   USER  165 

to  prevent  excessive  application  of  water,  because  where  per- 
mitted it  is  almost  certain  to  cause  an  injurious  rise  in  the  water 
table  and  the  resulting  injuries  from  rise  of  alkali,  water  logging 
etc.,  which  are  more  likely  to  occur  where  water  is  plentiful 
than  where  it  is  scarce.  It  is  thus  very  important  to  limit  the 
amount  of  water  supplied  to  that  actually  required  for  plant 
consumption,  as  nearly  as  this  can  be  attained  in  practice. 
This  requires  great  care,  both  in  preparation  of  the  land  and 
in  the  application  of  the  water,  and  no  measures  have  been 
found  more  efficient  than  those  which  engage  the  direct  financial 
interest  of  the  irrigator  by  charging  for  water  service  by  the 
quantity  of  water  used.  To  do  this  requires  careful  and  sys- 
tematic measurement  of  the  water  to  each  irrigator. 

The  standard  unit  for  the  measurement  of  flowing  water 
in  English-speaking  countries  is  the  cubic  foot  per  second.  This 
may  be  defined  as  a  stream  of  such  velocity  and  volume  that 
one  cubic  foot  of  water  passes  a  given  point  in  a  second  of  time. 
If  the  mean  velocity  of  the  stream  is  one  foot  per  second,  and  the 
cross-section  is  one  square  foot,  the  flow  is  one  cubic  foot  per 
second.  For  brevity  the  cubic  foot  per  second  is  called  a 
"  cusec  "  in  India,  and  in  America  it  is  called  a  "  second-foot." 
American  irrigators  often  use  another  unit  having  its  origin 
in  placer  mining,  called  the  "  miner's  inch,"  from  the  discharge 
of  a  square  inch  orifice  under  a  given  head.  The  varying  values 
of  this  unit  under  the  wide  variety  of  conditions  of  flow  created 
such  confusion  that  legislative  attempts  have  been  made  to 
define  the  miner's  inch  in  terms  of  the  standard  unit,  the  second- 
foot.  In  Colorado  the  statutes  provide  that  38.4  miner's  inches 
shall  equal  one  second-foot.  In  Arizona,  California,  Montana 
and  Oregon,  a  miner's  inch  is  one-fortieth  of  a  second-foot, 
while  in  Idaho,  Kansas,  Nebraska,  New  Mexico,  North  Dakota 
and  South  Dakota  it  is  one-fiftieth  of  a  second-foot,  and  in  other 
States  no  definite  values  have  been  assigned. 

This  variation  unfits  the  miner's  inch  for  use  as  a  common 
standard,  and  we  are  forced  to  adhere  to  the  second-foot  as  the 
standard  unit  for  expressing  the  volume  of  flowing  streams. 

Where  volume  is  considered  independent  of  the  element  of 


166  MEASUREMENT  OF  IRRIGATION   WATER 

time,  the  acre-foot  has  been  generally  adopted.  It  is  the  quantity 
of  water  that  will  cover  an  area  of  one  acre  to  the  depth  of  i 
foot,  and  is  hence  43,560  cubic  feet. 

As  a  subdivision  of  the  acre-foot,  acre-inch  is  often  used, 
being  one- twelfth  of  the  acre-foot,  or  3630  cubic  feet.  The 
acre-foot  is  an  especially  convenient  unit  of  volume  from  its 
ready  applicability  to  land  areas,  and  its  simple  relation  to 
the  second-foot.  A  stream  flowing  at  the  rate  of  i  cubic  foot 
per  second  will  discharge  about  2  acre-feet,  or  more  exactly, 
1.9835  acre-feet,  in  i  day  of  24  hours.  In  i  hour  it  will  discharge 
about  i  acre-inch. 

5.  Measuring  Devices. — The  devices  most  used  for  measuring 
irrigation  water  are  weirs,  submerged  orifices,  and  current 
meters,  all  these  being  accompanied  by  gages  showing  the 
stage  or  head  of  the  water  in  the  stream  measured.  Where 
there  is  sufficient  available  fall  the  weir  is  the  most  convenient 
and  almost  universal  measuring  device.  Where  there  is  less 
fall,  and  the  quantity  of  water  to  be  measured  is  small,  some 
form  of  orifice  can  be  used  and  is  less  affected  by  temporary 
variations  of  head  than  the  weir,  but  must  be  kept  free  from 
trash. 

Where  the  quantity  of  water  is  too  large  or  the  available 
head  is  insufficient  for  the  use  of  the  weir,  a  current  meter 
gaging  station  may  be  employed,  as  described  on  page  158. 

a.  Weirs. — A  weir  may  be  defined  as  a  wall  over  which  a 
stream  of  water  flows.  Experiments  have  shown  that  where 
the  conditions  are  well  defined  the  quantity  of  water  discharged 
over  a  weir  bears  a  definite  relation  to  the  depth  of  the  flow, 
and  by  keeping  this  constant,  or  by  noting  its  variations,  the 
quantity  of  water  passing  in  a  given  time  may  be  accurately 
measured.  This  relation,  however,  varies  with  the  length, 
shape  and  other  conditions  concerning  the  weir.  Weirs  are  of 
two  general  types,  namely,  free  weirs  and  submerged  weirs. 

A  free  weir  is  one  where  the  downstream  water  elevation  is 
lower  than  the  crest  of  the  weir. 

A  submerged  weir  is  one  where  the  downstream  water  eleva- 
tion is  higher  than  the  crest  of  the  weir.  A  free  weir  is  some- 


MEASURING  DEVICES  167 

times  converted  into  a  submerged  weir  by  increasing  the  dis- 
charge sufficiently  or  by  obstructing  the  stream  below  sufficiently 
to  cause  the  downstream  water  elevation  to  rise  above  the  level 
of  the  weir  crest. 

Where  the  sides  of  the  weir  are  placed  so  as  to  contract  the 
channel  in  which  the  weir  is  situated,  it  is  called  a  contracted 
weir,  and  where  the  sides  of  the  weir  are  coincident  with  the 
stream  it  is  called  a  suppressed  weir,  the  contractions  being 
in  this  case  suppressed. 

When  the  sides  of  a  weir  are  perpendicular  to  the  crest, 
it  is  called  a  rectangular  weir.  In  a  trapezoidal  weir,  the  sides 
make  obtuse  angles  with  the  crest.  A  common  form  of  trape- 
zoidal weir  is  called  the  Cippoletti  weir  in  which  the  sides  slope 
outward  from  the  crest  in  the  ratio  of  i  horizontal  to  4  vertical. 
It  is  so  designed  in  order  that  the  ratio  of  the  end  contractions 
of  the  sheet  of  water  to  its  depth  shall  be  constant. 

For  the  accurate  measurement  of  water,  weirs  should  be 
constructed  with  the  following  characteristics: 

1.  The   crest  and  sides  of  the  weir  should  be  sharp  and 
smooth,    and   should   be   distant   from   the   bottom   and   sides 
respectively,  both  above  and  below  the  weir,  not  less  than  three 
times  the  depth  of  water  on  the  weir. 

2.  The  crest  should  be  level  from  end  to  end. 

3.  The  upstream  face  of  the  weir  should  be  vertical. 

4.  Air  should  circulate  freely  under  the  overflowing  sheet. 

5.  The  cross-sectional  area  of  the  stream  above  the  weir 
should  be  not  less  than  seven  times  that  of  the  overflowing 
sheet  of  water. 

6.  The  depth  of  water  on  the  weir  should  be  not  more  than 
one- third  its  length. 

The  measurement  of  the  head  on  the  weir  should  be  the  actual 
elevation  of  the  water  surface  above  the  weir  crest,  from  5  to  10 
feet  upstream  from  the  weir.  Where  the  surface  velocity  of 
the  stream  is  more  than  3  feet  per  second  at  a  point  upstream 
from  the  weir  a  distance  of  ten  times  the  depth  on  the  weir, 
or  where  the  area  of  its  cross-section  is  less  than  six  times 
that  of  the  overflowing  sheet,  a  correction  must  be  made 


168  MEASUREMENT  OF  IRRIGATION   WATER 

for   velocity  of  approach,  which  increases   the   discharge  over 
the  weir. 

From  experiments  on  rectangular  weirs,  Francis  developed 
the  formula  : 


In  which  Q  =  the  quantity  discharged  in  second-feet; 

Z,  =  the  length  of  weir  in  feet; 
and          H  =  the  head  on  the  weir  in  feet. 

The  Cippoletti  weir  permits  a  simpler  formula  for  the  rea- 
sons above  given,  and  Cippoletti's  experiments  indicated  a 
slightly  higher  coefficient,  resulting  in  the  following: 


Where  conditions  encountered  indicate  a  velocity  of  approach 
sufficient  to  affect  the  result,  this  may  be  computed  from  the 
following  formula  : 


In  which  V  =  the  velocity  of  approach; 

Q  =  the  discharge  in  second-feet; 
and         A  =  the  area  of  cross-section  of  the  channel  of  approach. 

To  adapt  this  to  the  formulae,  V  should  be  converted  to  terms 
of  head  by  the  following  formula: 


In  which  h  =  the  head  due  to  velocity  of  approach. 

Where  this  results  in  a  considerable  value  for  //,  that  value 
may  be  substituted  for  h  in  the  following  formula  proposed  by 
Francis  for  cases  requiring  correction  for  velocity  of  approach  : 


The  corresponding  formula  for  Cippoletti  weirs  is: 


MEASURING  DEVICES  169 

.  Measuring  Orifices. — Where  the  amount  of  floating  debris 
is  negligible  or  can  be  thoroughly  controlled  and  the  quantity 
of  water  to  be  measured  is  not  too  great,  some  form  of  orifice 
is  perhaps  the  best  and  most  accurate  of  the  cheaper  forms  of 
canal  measurement.  It  can  be  used  with  smaller  loss  of  head 
than  required  for  a  weir,  and  the  results  are  less  affected  by 
errors  in  observing  the  head.  It  is  worthless,  however,  whenever 
it  is  liable  to  be  clogged  in  any  degree. 

An  orifice,  as  the  term  is  here  used,  is  any  form  of  opening 
in  the  wall  of  a  channel  entirely  below  the  surface  of  the  con- 
tained water.  The  wall  may  have  any  position  from  horizontal 
to  vertical,  and  the  water  may  discharge  either  into  water  or 
into  the  open  air.  If  it  discharges  into  air  it  is  said  to  be  free. 
When  it  discharges  into  water,  it  is  called  a  submerged  orifice. 

A  contracted  orifice  has  its  perimeter  located  far  enough 
from  the  bounding  surfaces  of  the  containing  channel,  so  that 
the  filaments  of  water  approaching  the  orifice  are  sharply 
deflected  in  passing  out,  and  by  their  inertia  contract  the 
issuing  stream  to  a  smaller  diameter  than  that  of  the 
orifice. 

A  suppressed  orifice  has  its  perimeter  so  nearly  coincident 
with  the  bounding  surfaces  of  the  channel  of  approach,  as  to 
eliminate  this  contraction.  Between  these  limits  are  many 
degrees  of  partial  contraction. 

If  the  opening  is  cut  in  a  wall  of  considerable  thickness,  or  if  a 
discharge  tube  is  attached,  it  requires  entirely  different  coeffici- 
ents from  a  simple  orifice. 

The  most  suitable  orifice  for  measurement  is  the  vertical 
sharp-edged  rectangular,  contracted,  submerged  orifice.  This 
type  can  be  accurately  reproduced  and  its  discharge  coefficient 
has  been  carefully  determined. 

The  thin,  sharp  edges  which  form  the  boundaries  of  the  orifice, 
must  be  at  sufficient  distance  from  the  boundaries  of  the  con- 
taining water  prism,  so  that  the  filaments  of  water  in  passing 
out  will  have  the  maximum  deflection  from  a  straight  line,  as 
they  enter  the  orifice,  and  thus  cause  the  maximum  contraction 
of  the  issuing  stream.  To  accomplish  this,  the  orifice  must  be 


170  MEASUREMENT  OF  IRRIGATION  WATER 

at  a  distance  from  the  bounding  surfaces  of  the  prism,  at  least 
twice  the  least  dimension  of  the  orifice.  The  upstream  face  of 
the  orifice  should  be  vertical,  and  the  sides  should  be  vertical. 
The  top  and  bottom  edges  of  the  orifice  should  be  parallel  and 
horizontal.  The  cross-sectional  area  of  the  water  prism  for 
25  feet  on  each  side  of  the  orifice,  should  be  at  least  six  times  the 
area  of  the  orifice.  The  head  on  the  orifice  to  be  used  in  com- 
putation is  the  actual  difference  in  elevation  between  the 
upstream  and  downstream  water  surfaces. 

As  irrigation  channels  are  usually  much  wider  than  their 
depth,  it  is  convenient  to  make  measuring  orifices  longer  than 
their  height.  To  simplify  computations  it  is  well,  if  practicable, 
to  have  the  cross-sectional  area  of  the  orifice  an  even  number 
of  square  feet.  A  length  of  2  feet  with  a  height  of  6  inches,  for 
example,  gives  an  area  of  i  square  foot,  which  is  the  most  con- 
venient area  of  all. 

The  formula  for  computing  the  discharge  of  the  standard 
rectangular  submerged  orifice  follows: 

Q  =  o.6i\/2gHA. 

• 

It  will  be  noted  that  the  discharge  of  the  orifice  varies 
with  the  square-root  of  the  head,  while  that  of  a  weir  varies  as 
the  cube  of  the  square-root  of  the  head.  For  this  reason  the 
former  is  more  accurate,  especially  under  conditions  where  the 
head  may  be  subject  to  temporary  unrecorded  fluctuations. 
For  the  same  reason  it  requires  considerably  more  velocity  of 
approach  to  sensibly  affect  the  discharge  of  an  orifice,  but  when 
this  is  considerable,  it  may  be  allowed  for  by  the  following 
formula  : 


the  symbols  having  the  same  significance  as  heretofore. 
This  need  seldom  be  used  where  the  conditions  of  accuracy 
are  properly  met. 

When  it  is  necessary  to  place  the  orifice  at  the  bottom  of  the 
channel  or  otherwise  to  suppress  a  portion  or  all  of  the  contrac- 


MEASURING  DEVICES  171 

tion  of  the  orifice,  the  discharge  may  be  approximately  obtained 
by  the  following  formula: 

Q  =  o.6i(i+o.i$r)\/2gHA, 

where  r  —  ratio  of  the  suppressed  portion  of  the  perimeter  to 
the  whole  perimeter  of  the  orifice,  and  the  other  symbols  have 
the  same  significance  as  heretofore  given. 

The  coefficients  in  this  formula  are  not  well  determined,  and 
cannot  be  made  as  exact  as  those  in  the  standard  orifice,  which  is 
more  accurately  reproducible. 

Notwithstanding  its  theoretical  accuracy,  the  uses  of  the 
orifice  are  limited  in  practice  by  three  important  conditions: 

1.  It  is  adapted  only  to  small  quantities  of  water. 

2.  Unless  very  large  it  is  often  liable  to  be  partially  clogged 
with  debris,  thus  vitiating  the  results. 

3.  The  necessity  of  observing  both  the  upstream  and  down- 
stream head. 

For  the  first  two  reasons  the  weir  is  generally  preferred  where 
sufficient  head  is  available  and  for  this  reason  the  free  orifice 
is  seldon  used  as  this  requires  as  much  head  as  a  weir;  it  may  be 
convenient,  however,  in  some  cases  where  it  is  desired  to  measure 
a  small  quantity  of  water  without  trash. 

Where  the  available  fall  for  measuring  a  canal  is  too  small, 
or  the  amount  of  sediment  too  great  to  permit  good  results 
from  the  use  of  weirs  or  orifices,  it  may  be  necessary  to  establish 
a  current-meter  gaging  station.  This  should  be  located  in  a 
straight  uniform  section  of  the  canal  with  clean  stable  banks 
and  bed,  where  velocities  are  unaffected  by  drops,  checks  and 
turnouts,  or  any  other  influence  likely  to  affect  the  relation  of 
gage  height  to  discharge,  upon  the  constancy  of  which  relation 
the  value  of  the  results  will  largely  depend. 

The  essential  elements  of  the  observations  are  frequent  or 
continuous  records  of  the  gage  height  at  the  station,  and  careful 
measurements  of  discharge  taken  at  various  stages  of  canal 
height,  to  indicate  points  of  control  by  which  a  curve  may  be 
plotted  which  shall  show  for  all  stages,  the  relation  of  gage 
height  to  discharge. 


172  MEASUREMENT  OF  IRRIGATION   WATER 

The  best  provision  for  current-meter  measurements  is  a 
bridge  spanning  the  canal  without  any  disturbance  of  the  flow 
by  piers  or  abutments.  This  should  be  divided  into  permanently 
marked  sections  of  10  feet  for  large  canals,  and  less  intervals 
for  small  ones.  At  each  station  the  depth  and  velocity  are 
carefully  measured,  and  an  assumption  made  that  each  measured 
result  is  the  mean  for  equal  distances  on  each  side  thereof,  so 
that  each  measurement  represents  one  of  the  sections.  The 
velocity  in  feet  per  second,  multiplied  by  the  depth  in  feet, 
multiplied  by  the  width  of  the  section,  will  give  the  discharge  in 
second-feet  of  that  section,  and  the  sum  of  the  discharges  of 
all  the  sections  will  be  the  discharge  of  the  canal. 

As  a  temporary  makeshift  the  velocity  of  the  canal  may 
be  measured  by  means  of  floats,  but  where  measurements  are 
to  be  made  frequently,  both  accuracy  and  economy  require 
that  the  current  meter  should  be  employed.  The  meters  and 
their  use  are  described  on  page  157. 

Whether  measurements  are  made  on  weirs,  orifices  or  with 
current  meters,  they  require  records  of  gage  height  in  order  to 
determine  the  discharge.  In  a  canal  wherein  the  discharge  is 
kept  practically  constant,  it  is  sufficient  to  read  the  gage  twice 
a  day,  with  additional  readings  whenever  the  quantity  of  water 
flowing  is  changed.  Where  changes  are  frequent,  either  from 
changing  the  position  of  the  headgates  or  from  changes  in  the 
quantities  taken  out  by  laterals,  an  automatic  instrument  should 
be  employed  to  make  a  continuous  record. 

Various  forms  of  water  meters  have  been  extensively  used 
where  greater  accuracy  is  required  than  can  be  obtained  with 
weirs  and  orifices,  or  where  conditions  make  their  use  convenient. 
In  general  they  are  too  expensive  for  practical  application  to 
the  measurement  of  irrigation  water,  except  where  this  is  very 
valuable. 

Where  a  small  quantity  of  water  is  delivered  through  pipes, 
the  ordinary  water  meter  used  for  city  supplies  is  the  most 
convenient  and  suitable.  It  consists  of  a  set  of  blades  caused 
to  revolve  by  the  passing  water,  and  an  indicator  recording  the 
revolutions  of  the  blades. 


MEASURING  DEVICES 


173 


When  mechanically  perfect  they  are  very  accurate,  but 
they  are  too  complicated  and  expensive  for  irrigation  use,  and 
are  not  suitable  for  measurement  of  the  large  quantities  of  water 
required  in  irrigation. 

The  rate  of  discharge  through  the  weirs  and  orifices  described 
depends  upon  the  head  of  water  above,  and  in  the  cases  of 
submerged  weirs  and  orifices,  the  elevation  of  the  water  below 
must  also  be  known.  It  thus  becomes  necessary  to  keep  a 
record  of  these  elevations,  and  this  attention  is  the  principal 
part  of  the  cost  of  water  measurement  by  these  methods.  If 
the  gages  are  read  only  at  intervals  by  an  observer,  no  account 
is  had  of  fluctuations  between  observations,  and  serious  inac- 
curacies may  be  involved.  Devices  are  therefore  employed  to 
make  and  keep  a  continuous  automatic  record  of  the  gage 


FIG.  54. — Rectangular  Measuring  Weir. 

height,  and  these  again  involve  expense,  and  complicated  clock- 
work and  recording  apparatus  liable  to  disarrangement,  and 
requiring  considerable  skill  for  repair.  Several  recording  devices 
of  reasonable  simplicity  and  efficiency  are  obtainable  from 
instrument  makers,  all  dependent  upon  the  rise  and  fall  of  the 
water  as  indicated  by  a  float  controlling  a  pen  on  a  dial  or 
cylinder  driven  by  weights  and  regulated  by  clockwork. 

c.  Banna  Meter. — F.  W.  Hanna  has  invented  a  recording 
device  designed  not  only  to  record  the  height  of  the  water  but  to 
translate  this  into  discharge  and  to  give  the  results  in  acre- feet, 
which  it  indicates  on  a  counter.  This  machine  is  also  controlled 
by  a  float,  driven  by  weights  and  regulated  by  clockwork. 
Its  advantage  over  the  standard  automatic  gage  is  that  it 
eliminates  the  need  of  using  a  table  for  interpreting  the  record. 
It  is  however,  more  complicated,  of  course. 


174 


MEASUREMENT  OF  IRRIGATION  WATER 


To  obviate  the  necessity  of  keeping  and  recording  gage 
heights,  and  also  to  secure  uniformity  of  flow,  various  devices 
have  been  proposed  to  keep  the  head  constant  over  weirs  or 
orifices,  some  of  which  are  in  limited  use. 

d.  The  Azusa  hydrant  is  simply  a  series  of  submerged  orifices 
of  different  sizes  which  may  be  opened  or  closed  at  will,  in 
accordance  with  the  quantity  of  water  desired.  To  keep  a 


FIG.  55.— Foote's  Measuring  Weir,  A.    Water  Divisor,  B. 

constant  head,  a  weir  is  provided  in  the  canal  just  below  the 
hydrant,  and  an  opening  in  this  so  adjusted  as  to  keep  the  water 
in  the  canal  just  above  the  crest  of  the  weir.  If  the  weir  is  made 
with  very  long  crest,  any  rise  of  water  in  the  canal  will  mostly 
pass  over  the  weir,  but  will  also  somewhat  increase  the  discharge 
through  the  orifices. 

e.  The  Foote  Measuring  box  is  a  device  adjustable  to  cause 
any  desired  quantity  of  water  to  flow  nearly  constantly,  and  so 


MEASURING  DEVICES  175 

arranged  as  to  measure  this  in  miner's  inches.  It  consists  of  a 
box  flume  fitted  into  the  ditch  from  which  the  water  is  to  be 
measured.  This  flume  is  divided  longitudinally  into  two  com- 
partments of  unequal  sizes,  and  the  entrance  of  water  into  each 
is  controlled  by  flash  boards,  so  that  in  use,  the  water  stands 
3  or  4  inches  higher  in  the  small  compartment  than  in  the  large 
one.  The  small  compartment  is  closed  at  the  lower  end,  and 
provided  with  a  spillway  into  the  large  one,  over  which  the 
water  flows  when  it  reaches  a  certain  depth.  On  the  opposite 
side  of  the  small  compartment  is  a  long  horizontal  slot  4  inches 
high,  the  center  of  which  is  4  inches  below  the  crest  of  the  spill- 
way, and  closed  by  a  gate  sliding  horizontally,  adjustable  to  a 
scale,  so  that  the  opening  may  be  adjusted  to  any  length  from 
zero  up  to  the  entire  length  of  the  slot.  The  area  of  the  open- 
ing in  square  inches  is  thus  four  times  the  length  of  the  opening 
as  adjusted,  and  when  the  water  stands  at  the  crest  of  the  spill- 
way, or  4  inches  above  the  center  of  the  slot,  the  area  of  the 
opening  expresses  the  discharge  in  miner's  inches.  The  success- 
ful use  of  this  measuring  device  requires  the  loss  of  4  or  5  inches 
of  head  in  the  supply  lateral,  and  about  a  foot  into  the  receiving 
lateral.  It  is  therefore  not  adapted  to  use  where  such  heads 
are  not  available,  but  is  otherwise  convenient  and  reasonably 
accurate. 

Many  similar  devices  have  been  proposed  and  used  to  some 
extent,  which  are  merely  more  or  less  ingenious  combinations 
of  weirs  and  orifices?  some  of  which  are  described  in  detail  in 
Bulletin  No.  247  of  the  Agricultural  Experiment  Station  of 
Berkeley,  California. 

All  such  weirs  and  orifices  require  considerable  loss  of  head 
and  a  great  deal  of  attention  to  the  stage  of  water,  involving  an 
automatic  time  register  if  any  great  accuracy  is  required.  To 
avoid  these  objections,  several  devices  have  been  invented  to 
measure  the  quantity  of  water  more  directly,  without  so  much 
loss  of  head,  and  with  increase  of  simplicity  of  mechanism. 

/.  The  Dethridge  meter  is  a  paddle  wheel  consisting  of  a  drum 
on  a  horizontal  axle,  with  projecting  blades  of  metal  attached 
at  equal  intervals  to  the  periphery  of  the  drum,  revolving  in  a 


176  MEASUREMENT  OF  IRRIGATION  WATER 

box  or  flume,  in  which  it  fits  closely  without  touching,  so  that 
very  little  water  can  pass  without  moving  the  blade  and  turning 
the  wheel.  The  bottom  of  the  box  is  curved  to  correspond  to 
the  circular  path  of  the  blades,  so  that  in  passing,  a  blade  does  not 
leave  the  proximity  of  the  bottom  until  the  next  blade  reaches 
it,  and  so  that  in  use,  the  water  always  fills  the  box  up  to  the 
bottom  of  the  drum. 

By  recording  the  revolutions  of  the  wheel,  information  is 
obtained  which  can  be  readily  translated  into  terms  of  flow. 
The  axis  of  the  wheel  can  be  attached  directly  to  a  counter  by 
reading  which  the  revolutions  are  obtained,  and  by  multiplying 
the  velocity  thus  obtained  by  the  cross-section  of  the  space 
through  which  the  water  passes  under  the  drum,  the  discharge 
is  obtained  directly,  affected,  however,  by  the  leakage  past  the 
vanes,  which  in  turn  is  affected  by  the  friction  involved  in 
turning  the  wheel.  A  well-made  instrument  of  this  kind  is 
very  accurate,  and  measures  the  water  with  a  very  slight  fall, 
depending  on  the  quantity  passing.  It  will  give  satisfactory 
results  with  quantities  varying  between  maxima  and  minima 
in  the  ratio  of  5  to  i.  In  practice  the  box,  if  of  wood,  is  liable 
to  warp  slightly,  and  thus  vary  the  clearance  around  the  blades, 
or  the  friction  of  turning,  or  both,  which  changes  the  coefficient 
of  discharge.  For  this  reason,  the  direct  method  of  inferring 
the  discharge  from  the  cross-section  and  wheel  readings  is  some- 
times rather  rough  and  it  is  better  to  have  a  rating  for  the 
coefficient  of  discharge  by  actually  measuring  the  discharge 
at  the  various  stages.  This  rating  should  be  renewed  whenever 
conditions  change  perceptibly.  It  is  best  to  construct  the 
box  surrounding  the  wheel  of  rich  concrete  carefully  smoothed, 
and  if  this  be  properly  founded,  little  change  need  be  expected. 
This  meter  can  be  built  of  any  size  desired.  It  is  moderate  in 
cost,  is  extremely  simple  in  principle,  in  construction  and  in 
operation.  It  gives  satisfactory  results,  with  very  small  loss 
of  head,  but  requires  attention  to  prevent  interruption  if  much 
floating  drift  is  passing. 

g.  The  Hill  meter,  devised  by  Louis  C.  Hill,  consists  of  a 
short  box  or  pipe  in  the  form  of  an  inverted  siphon,  through 


MEASURING  DEVICES  177 

which  the  water  to  be  measured  is  made  to  pass,  the  issuing 
end  being  vertical  and  lower  than  the  other  and  somewhat 
smaller.  As  the  water  rises  through  the  issuing  end  of  the 
siphon,  it  passes  a  set  of  inclined  vanes  attached  to  a  central 
drum  revolving  on  a  pivot,  and  the  flowing  water  striking  the 
inclined  vanes  turns  the  drum,  the  axis  of  which  drives  a  counter 
so  arranged  on  a  dial  as  to  register  the  passing  water  directly 
in  acre-feet.  A  single  opening  and  meter  can  be  used  with  an 
accuracy  of  about  2  per  cent,  over  a  range  from  i  minimum  to  5 
maximum. 

Unless  the  entrance  of  the  siphon  is  well  screened  the  meter 
is  liable  to  be  choked  by  floating  weeds  or  other  drift. 

When  kept  free  from  drift  and  properly  built,  this  meter  is 
very  accurate,  reliable  and  simple.  It  requires  very  little  loss 
of  head  in  the  measured  water. 

h.  The  Grant-Mitchell  or  Australian  meter  is  used  to  some 
extent  in  Australia,  and  is  similar  in  principle  to  the  Hill  meter. 
It  is,  however,  more  expen- 
sive, and    seems  to   have  no 
special  advantages  over  that 
instrument,    but    is    said    to 
give  good  results.     Both  are 
patented. 

i.  The  Venturi  meter  is 
a  very  simple  and  accurate 
device  for  measuring  water, 
much  used  on  city  water 
supply,  and  recently  intro- 

J         .     .          FIG.  56.— Australian  Water  Meter. 

duced  to  some  extent  on  irri- 
gation works.  The  water  is  conducted  under  pressure  through 
a  pipe  which  is  gradually  and  gently  contracted,  and  then 
still  more  gradually  returns  to  its  normal  dimensions.  In 
passing  through  the  contracted  throat,  the  velocity  of  the 
water  is  increased  in  the  same  ratio  that  the  cross-section 
of  the  pipe  is  diminished.  By  this  means  a  portion  of  the 
pressure  head  is  converted  into  velocity  head,  and  by 
measuring  the  pressure  at  a  point  before  contraction  begins, 


178 


MEASUREMENT  OF  IRRIGATION   WATER 


and  also  at  the  contracted  throat,  the  quantity  of  water  passing 
may  be  computed  from  the  following  formula: 


Q  =  Ca 


in  which   a  =  the  area  at  the  throat; 

A  =  area  of  the  pipe  before  contraction; 
h  =  pressure  head  at  A—  same  at  a; 
C  =  a  coefficient  usually  from  .97  to  .99,  dependent  on 
the  perfection  of  the  meter. 


Chart  Recorder 
continuously  Records 
cubic  feet  per  second 


FIG.  57. — Venturi  Meter  and  Recording  Device  on  Lateral  Head. 

The  only  complication  about  this  meter  is  the  measurement 
and  registration  of  the  pressures,  a  and  A.  Elaborate  electric 
devices  are  sometimes  used  for  this,  which  are  very  accurate 
but  too  expensive  for  irrigation  uses.  Floats  can  be  used  in 
connection  with  the  ordinary  automatic  gages,  which  will  give 
approximate  results  if  kept  in  order. 

j.  Venturi  Flume. — Mr.  D.  C.  Hermy  has  proposed  a  simple 
and  cheap  modification  of  the  Venturi  meter,  called  the  "  Venturi 
Flume."  In  this  flume  a  contraction  is  effected  by  a  curved 
metal  or  reinforced  concrete  sheet  placed  between  the  sides  of 
the  flume,  depressing  the  surface  of  the  water.  At  the  point 
of  greatest  depression  the  sheet  is  for  a  few  inches  parallel 


MEASURING  DEVICES  179 

with  the  floor  of  the  flume  and  is  pierced  by  several  holes  allow- 
ing water  to  rise  above  the  sheet.  One  gage  is  installed  in 
the  flume  above  the  measuring  device,  and  the  second  one 
in  the  still  water  pond  formed  by  the  curved  sheet  and  the  sides 
of  the  flume.  From  the  reading  of  these  two  gages  "  H  "  is 
found,  from  which  the  flow  may  be  calculated  by  the  above 
formula. 

The  device  was  tested  in  1915  in  various  forms  on  four 
projects  of  the  Reclamation  Service,  the  flow  being  checked 
by  weir  measurements.  The  quantity  of  water  varied  in  these 
experiments  between  i  second-foot  and  7  second-feet,  and  the 
throat  velocity  from  i  to  SyV  feet  per  second.  These  showed 
deviations  from  correct  results  varying  from  about  i  to  about 
ii  per  cent  of  the  quantity  of  water  measured,  the  more  accurate 
results  being  generally  obtained  with  the  larger  quantities 
of  water. 

The  loss  of  head  through  the  throat  varies  between  .03 
foot  and  .05  foot,  being  greater  for  the  higher  velocities  and  for 
the  smaller  quantities  of  water.  The  loss  varied  from  13  per 
cent  to  56  per  cent  of  the  velocity  head. 

Losses  exceeding  40  per  cent  of  the  velocity  head  at  the  throat 
occur  only  for  height  of  throat  less  than  3  inches.  With  a 
throat  height  of  4  inches  or  over  the  losses  are  from  24  per  cent 
down,  the  tendency  being  to  a  reduction  of  percentage  as  the 
velocity  increases,  although  the  actual  loss  of  head  may  be 
greater. 

This  measuring  device,  especially  in  the  smaller  sizes,  is  liable 
to  clog  with  large  weeds,  but  passes  leaves  and  other  small  trash. 
It  has  not  been  commercially  manufactured. 

In  1915  Mr.  V.  M.  Cone  of  the  United  States  Department  of 
Agriculture  designed  and  experimented  with  another  form  of 
"  Venturi  Flume  "  in  which  contraction  is  effected  by  drawing 
in  the  sides  of  the  flume,  leaving  the  water  surface  free.  Experi- 
ments on  this  type  of  flume  were  made  in  connection  with  some 
of  those  of  the  Henny  flume  above  described.  The  experiment 
showed  that  below  a  flow  of  2  second-feet  the  coefficient  fluctuates 
erratically  with  unreliable  results.  Above  this  amount  the 


180 


MEASUREMENT  OF  IRRIGATION  WATER 


TABLE  XXVIL— DISCHARGE  OF  STANDARD  RECTANGULAR  SUB- 
MERGED ORIFICES  IN  CUBIC  FEET  PER  SECOND,  COMPUTED 
FROM  THE  FORMULA  Q  =  o.6iV^H.  A 


Head  H, 
Feet 

Cross-sectional  Area  A   of  Orifice,  Square  Feet 

0.25 

0.5 

0-75 

i  .0 

1.25 

1-5             i.  75 

2.O 

O.OI 

O.  122 

0.245 

0.367 

0.489 

0.611 

0-734 

0.856 

0.978 

O.O2 

0.173 

0.346 

0.518 

0.691 

0.864 

1-037 

I  .  2IO 

1.382 

0.03 

O.  212 

0.424 

0-635 

0.847 

1-059 

I.27I 

1.483 

1.694 

0.04 

0.245 

0.489 

0-734 

0.978 

1.223 

1.468 

I.7I2 

1-957 

0.05 

0.273 

0-547 

0.820 

1.093 

1.367 

1  .640 

I-9I3 

2.186 

O.o6 

0.300 

0-599 

0.899 

1.198 

1-497 

1.797 

2.097 

2.396 

0.07 

0.324 

0-647 

0.971 

1.294 

i  .617 

1.941 

2-265 

2.588 

0.08 

0.346 

0.691 

1.037 

1-383 

1.729 

2-074 

2.42O 

2.766 

O.OQ 

0.367 

0-734 

I  .  IOI 

1.468 

1-835 

2.  2OI 

2.638 

2-935 

O.  IO 

0.387 

0-773 

i  .  160 

1-557 

1-933 

2.320 

2.707 

3-094 

O.  II 

0.406 

0.811 

1.217 

i  .622 

2.027 

2-433 

2.839 

3-244 

O.  12 

0.424 

0.847 

1.271 

1.694 

2.118 

2.542 

2.965 

3-389 

0.13 

0.441 

0.882 

1-323 

1.764 

2.  2O5 

2-645 

3-086 

3-527 

0.14 

0.458 

0.915 

1-373 

1.830 

2.287 

2-745 

3  .  203      3  .  660 

0.15 

0.474 

0.947 

i  .421 

1.895 

2.369 

2.842 

3.316      3.790 

0.16 

0.489 

0.978 

1.467 

1.956 

2-445 

2-934 

3-423 

2.912 

0.17 

0.504 

1.008 

1.512 

2.016 

2.520 

3.024 

3-528 

4.032 

0.18 

0-5I9 

1-037 

I-556 

2.075 

2-593 

3.II2 

3-631 

4-150 

0.19 

0-533 

i.  066 

1-599 

2.132 

2.665 

3.198 

3-731 

4.264 

o.  20 

0-547 

1.094 

1.641 

2.188 

2-735 

3.282 

3.829 

4-376 

0.21 

0.561 

1.  1  20 

1.681 

2.  241 

2.801 

3-36I 

3.921 

4.482 

O.  22 

0-574 

1.148 

1.722 

2.  296 

2.870 

3.464 

4.018 

4-592 

0.23 

0.587 

1.172 

1-759 

2-345 

2.931 

3-517 

4-103 

4.690 

0.24 

0.600 

1.198 

1-797 

2.396 

2-995 

3-599 

4-193 

4.792 

0.25 

0.612 

1.223 

1-834 

2.446 

3-057 

3.668 

4.280 

4.891 

0.26 

0.624 

1.247 

1.871 

2.494 

3-II7 

3-741 

4-365 

4.988 

0.27 

0.636 

1.270 

1.906 

2.541 

3.176 

3.811 

4-446 

5.082 

0.28 

0.646 

1.294 

1.942 

2.589 

3-236 

3-883 

4-530 

5.178 

o.  29 

0.659 

i-3i9 

1.978 

2.638 

3-297 

3-956 

4.616 

5.276 

0.30 

0.670 

1-339 

2.009 

2.678 

3-347 

4-017 

4.687 

5-356 

MEASURING  DEVICES 


181 


TABLE  XXVII.— Con  tin  ncd 


Head  //, 

Cross-sectional  Area  A  of  Orifice,  Square  Feet 

Feet 

0.25 

o.S 

0.75 

i  .0 

1.25 

i.  5 

1.75 

2.0 

0.31 

0.681 

I-363 

2.045 

2.  726 

3.407 

4.089 

4-771 

5-452 

0.32 

0.692 

1.382 

2.073 

2.764 

3-455 

4.146 

4.837 

5.528 

0-33 

0.703 

I-405 

2.  IO7 

2.810 

3-5I3 

4-215 

4.917 

5.62O 

0-34 

0.713 

1  .426 

2.139 

2.852 

3-565 

4.278 

4.991 

5.704 

0-35 

0.724 

1.446 

2.  169 

2.892 

3-615 

4.338 

5.061 

5.784 

0.36 

0-734 

1.467 

2.  201 

2-934 

3-667 

4.401 

5-135 

5.868 

0-37 

0-745 

1.488 

2.232 

2.976 

3.720 

4.464 

5.208 

5-952 

0.38 

0-754 

1.508 

2.  262 

3.0l6 

3-770 

4.524 

5-278 

6.032 

0-39 

0.764 

1.527 

2.291 

3-054 

3.818 

4.582 

5-345 

6.  109 

0.40 

0-774 

1-547 

2.321 

3-094 

3.867 

4.641 

5.415 

6.188 

0.41 

0.783 

i-S67 

2-350 

3-133 

3.917      4-7oo 

5.483 

6.266 

0.42 

0.792 

1-585 

2-377 

3.170 

3.962      4-754 

5-547 

6-339 

0-43 

0.802 

i  .604 

2.406 

3.208 

4.010      4.812 

5-614 

6.416 

0.44 

O.Sll 

1.622 

2-433 

3-244 

4.055      4.866 

5-677 

6.488 

0-45 

0.820 

i  .  640 

2.461 

3.28l 

4.101      4.921 

5-741 

6.562 

0.46 

0.829 

1.659 

2.489 

3.318 

4-147 

4-977 

5-807 

6.636 

0.47 

0.839 

1.678 

2.517 

3-356 

4-195 

5-035 

5-874 

6.713 

0.48 

0-847 

1.695 

2-542 

3.389 

4.237      5.084 

5-931 

6.778 

0.49 

0.856 

1.712 

2.568 

3-424 

4.280      5.136 

5-992 

6.848 

0.50 

0.805 

1.729 

2-594 

3.458 

4-323      5-i88 

6.052 

6.917 

0.52 

0.882 

1.763 

2.645 

3-527 

4.409 

5-290 

6.  172 

7-054 

0-54 

0.898 

1.797 

2-695 

3-593 

4.491 

5-390 

6.288 

7.186 

0.56 

0.915 

i  .  830 

2-745 

3.660 

4-575 

5-490 

6.405 

7.320 

0.58 

0.931 

1.862 

2-794 

3-725 

4.656 

5.587 

6.518 

7-450 

0.60 

0.947 

1.895 

2.842 

3-790 

4-737 

5-684 

6.632 

7-579 

0.62 

0.963 

1-925 

2.887 

3-850 

4.812 

5-775 

6.737 

7.700 

0.64 

0.978 

1.956 

2-934 

3.912 

4.890 

5.868 

6.846 

7.824 

0.66 

0-993 

1.987 

2.980 

3-974 

4.967 

5.960 

6-954 

7-947 

0.68 

1.008 

2.016 

3.024 

4-032 

5.040 

6.048 

7.056 

8.064 

0.70 

1.023 

2.046 

3.069 

4.092 

5-II5 

6.138 

7.161 

8.184 

0.72 

1.038 

2.076 

3-II4 

4-152 

5-I90 

6.228 

7.266 

8.304 

0.74 

1  .052 

2.  104 

3.158 

4.  210 

5-  260 

6.311 

7-369 

8.421 

o.  76 

1.  066 

2.132 

3.198 

4.264 

5-330 

6.396 

7.462 

8.528 

0.78 

1.  080 

2.  160 

3.240 

4.320 

5.400 

6.480 

7.560 

8.640 

0.80 

1.094 

2.188 

3.282 

4-376 

5-470 

6-564 

7-658 

8.752 

182  MEASUREMENT  OF  IRRIGATION  WATER 

accuracy  is  about  the  same  as  that  for  the  Henny  flume.  It 
has  the  disadvantage  that  the  formula  by  which  the  flow  is  to  be 
calculated  must  take  into  account  not  only  "  H  "  but  also 
separately  the  depth  at  either  of  the  two  gages.  Stilling  boxes 
are  necessary  with  high  velocities  to  permit  accurate  observations 
of  the  surface  of  the  swiftly  flowing  water.  It  has  the  advantage, 
however,  of  being  less  easily  clogged  with  drift,  as  the  upper 
surface  is  free  from  obstruction. 

The  successful  and  practical  meter  for  measuring  water  to 
each  farm  must  be  both  simple  and  cheap.  It  is  used  so  fre- 
quently that  any  complication  or  trouble  with  each  one  aggre- 
gates a  large  amount  and  hence  the  importance  of  simplicity 
and  reliability.  This  extends  also  to  the  formula  for  computing 
results.  It  is  important  to  have  these  computations  worked 
out  and  tabulated  for  all  possible  cases,  not  only  for  convenience 
and  economy  of  time,  but  also  to  eliminate  liability  to  errors. 

One  of  the  greatest  economies  possible  in  the  measurement 
of  water  is  the  use  of  the  rotation  system,  by  which  each  irriga- 
tor  takes  a  much  larger  quantity  of  water  than  he  would  be 
entitled  to  continously,  and  shortens  the  time  of  use  propor- 
tionately, allowing  his  neighbors  to  do  the  same.  By  this  means 
it  is  necessary  to  measure  the  quantity  used  by  all  those  who 
rotate  together,  and  the  length  of  time  this  volume  is  received 
by  each  indicates  the  total  quantity  each  receives.  This  reduces 
the  number  of  measurements  to  be  made  by  meter,  and  is  more 
accurate  than  meter  measurements  to  individuals,  as  the  time 
of  delivery  to  each  user  can  be  easily  determined  to  a  second  if 
desired,  which  is  a  much  closer  measurement  than  any  meter 
measurement.  This  is  one  of  the  minor  advantages  of  the 
rotation  system. 

In  the  present  state  of  the  art,  the  weir,  either  rectangular 
or  Cipolletti,  is  the  most  practicable  meter  for  irrigation  pur- 
poses. If  great  accuracy  is  required,  the  mechanical  register  is 
employed  to  record  the  head,  and  if  the  forebay  is  kept  clean 
good  results  are  obtained. 


MEASURING  DEVICES  183 


REFERENCES  FOR  CHAPTER  XI 

CARPENTER,  L.  G.    Measurement  and  Division  of  Water.     Bulletin  No.  27,  State 

Agricultural  College.     Fort  Collins,  Col.,  1894. 
CHURCH,  IRVING  P.     Mechanics  of  Engineering:    Fluids.     John  Wiley  &  Sons, 

New  York. 
FANNING,  J.  T.     Hydraulic  and  Water-supply  Engineering.     D.  Van  Nostrand 

&  Co.,  New  York,  1890. 
FLINN,  A.  D.,  and  DYER,  C.  W.  D.     The  Cippoletti  Trapezoidal  Weir.    Trans. 

Am.  Soc.  C.  E.,  Vol.  XXXII.     New  York,  July,  1894. 
FLYNN,  P.  J.     Irrigation  Canals  and  Other  Irrigation  Works,  and  Flow  of  Water 

in  Irrigation  Canals.     Denver,  Col.,  1892. 
GREEN,  J.  S.     Fourth  Biennial  Report  State  Engineer  of  Colorado.     Denver, 

Col.,  1889. 
HORTON,    ROBERT   E.    Weir   Experiments,    Coefficients   and    Formulas.     U.    S. 

Geological  Survey,  Water  Supply  Paper  No.  200.     Washington,  D.  C.,  1907. 
HOYT,  J.  C.,  and  GROVER,  N.  C.     River  Discharge.     John  Wiley  &  Sons.    New 

York,  1907. 

MULLINS,  Lieut.-Gen.  J.    Irrigation  Manual.     E.  &  F.  N.  Spon,  New  York,  1890. 
MURPHY,  E.  C.     Accuracy  of  Stream  Measurements.     U.  S.  Geological  Survey, 

Water  Supply  Paper  No.  94.     Washington,  D.  C.,  1904. 
MURPHY,  E.  C.,  HOYT,  J.  C.,  and  HOLLISTER,  G.  B.     Hydrographic  Manual, 

U.  S.  Geological  Survey,  Washington,  D.  C.,  1904. 

NEWELL,  F.  H.     Part  II,  nth  and  i3th  Annual  Reports  U.  S.  Geological  Sur- 
vey, Washington,  D.  C.,  1890  and  1892. 
WEISBACH,  P.  J.     Hydraulics  and  Hydraulic  Motors.     Translated  and  Edited 

by  A.  Jay  Du  Bois.     John  Wiley  &  Sons,  New  York,  1891. 
HANNA,  F.  W.     Measurement  of  Water  for  Irrigation,  U.  S.  R.  S.  Handbook. 
DRAKE,  E.  F.     Report  of  Hydrometric  Surveys  for  1916,  Dept.  of  Interior,  Ottawa, 

Canada. 
SCOBEY,  F.  C.     Flow  of  Water  in  Irrigation  Channels.     Bulletin  194,  U.  S.  Office 

of  Experiment  Stations. 
CONE,  V.  M.     The  Venturi  Flume.     Journal  of  Agricultural  Research,  Vol.  IX, 

No.  4.     Washington,  D.  C. 
MEAD,  DANIEL  W.     Water  Power  Engineering.     McGraw-Hill  Book  Co.,  New 

York. 
BARK,  DON  H.     Experiments  on  the  Economical  use  of  Water  in  Idaho.     Bulletin 

339,  U.  S.  Office  of  Public  Roads  and  Rural  Engineering. 
Some  Measuring  Devices  used  in  the  Delivery  of  Irrigation  Water.     Bulletin  247, 

Agr.  Exp.  Sta.,  University  of  California,  Berkeley,  Cal. 
MORITZ,  E.  A.     Flow  of  Water  in  Pipes,    Eng.  Record,  Vol.  LXVIII,  page  667. 


CHAPTER  XII 
DRAINAGE 

FOR  the  health  and  vigor  of  the  most  useful  plants,  the  roots 
require  air  just  as  certainly  as  they  require  water.  If  the  soil  in 
the  root  zone  is  saturated  with  water  this  excludes  the  air,  and 
if  this  continues  for  any  considerable  length  of  time  the  plant 
suffers  and  eventually,  unless  this  is  corrected,  it  dies.  There 
is  much  difference  in  the  rapidity  with  which  various  plants 
are  so  affected,  and  a  few  water-loving  plants  require  their 
roots  to  be  in  saturated  soils  for  the  best  results.  The  tules, 
rushes,  water  grasses  and  willows  are  the  commonest  spontaneous 
growths  of  this  kind,  and  several  varieties  of  coarse  grasses 
also  thrive  in  wet  places.  The  principal  useful  plants  which 
grow  best  in  saturated  ground  are  rice,  cranberries,  and  some 
varieties  of  dates. 

It  is  difficult  in  most  localities  to  apply  to  the  surface  of  the 
land  in  irrigation,  sufficient  water  for  the  maximum  crop  pro- 
duction, without  allowing  a  considerable  quantity  of  the  water 
applied  to  escape  to  the  underlying  water  table.  In  addition 
to  this,  every  irrigated  region  is  traversed  by  numerous  canals 
and  laterals,  continually  wet  during  the  irrigation  season, 
from  which  water  steadily  percolates  downward  to  the  water 
table  in  considerable  quantity  unless  the  canals  are  well  lined 
with  concrete. 

For  these  reasons  it  generally  occurs  that  after  a  large  valley 
has  been  irrigated  for  a  few  years,  the  ground  water  begins  to 
rise,  and  unless  there  is  free  escape  through  coarse  subsoils  to 
deep  drainage  lines,  the  water  table  rises  to  a  point  where  it 
injures  vegetation,  and  wherever  it  continues  to  rise,  it  eventu- 
ally kills  all  vegetation  except  aquatic,  or  water-loving  plants. 
This  generally  occurs  first  in  low  places,  and  ponds  and  marshes 

184 


SIGNS  OF  SEEPAGE  185 

are  apt  to  form  which  gradually  increase  in  area  unless  means 
are  taken  to  prevent  or  cure  the  trouble.  This  result  is  so 
universal  that  there  is  scarcely  a  large  valley  in  the  world 
that  has  been  irrigated  for  several  years  that  does  not  have 
trouble  with  seepage,  and  a  problem  of  drainage.  In  many 
places  this  result  is  wide-spread  and  disastrous. 

It  is  said  that  large  areas  in  India,  formerly  subject  to  occa- 
sional famines  caused  by  failure  of  crops  on  account  of  drouth 
were  relieved  by  irrigation  works  to  counteract  the  drouths 
only  to  find  that  the  mortality  from  malaria  induced  by  the 
marshes  resulting  from  irrigation  was  greater  than  that  formerly 
due  to  famine.  Large  areas  in  Egypt  have  been  abandoned 
on  account  of  the  rise  of  ground  water  and  accompanying 
alkaline  conditions. 

In  the  Murgab  Valley  in  Turkestan  the  irrigated  lands  have 
been  largely  abandoned  on  account  of  the  rise  of  water  and 
alkali,  and  the  canals  built  to  new  lands. 

Large  areas  in  the  Valley  of  California  have  had  their  fertility 
reduced  or  destroyed  from  the  same  cause. 

In  the  San  Luis  Valley  of  Southern  Colorado,  where  irriga- 
tion has  been  widely  practiced,  nearly  400,000  acres  of  land 
have  been  waterlogged. 

The  Rio  Grande  Valley  in  New  Mexico  and  Texas  shows 
extensive  results  of  high  water  table  and  alkali. 

Many  of  the  projects  recently  built  by  the  U.  S.  Reclamation 
Service  already  show  similar  problems  which  have  been  or  are 
being  met  by  the  construction  of  drainage  works. 

It  is  thus  evident  that  the  subject  of  drainage  and  swamp 
reclamation  is  a  necessary  branch  of  irrigation  engineering 
and  should  be  studied  as  such. 

i.  Signs  of  Seepage. — No  definite  rules  can  be  formulated 
to  indicate  where  seepage  is  likely  first  to  appear  or  to  develop  as 
irrigation  proceeds.  A  careful  study  of  soil  and  topographic 
conditions  may  furnish  evidence  to  indicate  whether  seepage  is 
likely  to  occur,  but  it  is  seldom  that  the  movements  of  ground 
water  can  be  foretold  with  any  certainty,  and  trouble  is  often 
experienced  where  least  expected.  For  this  reason  it  is  impracti- 


186  DRAINAGE 

cable  to  wisely  plan  and  construct  drainage  works  for  irrigated 
lands  in  advance  of  their  actual  irrigation. 

It  is  nevertheless  very  important  that  the  rise  and  movement 
of  the  ground  water  be  closely  observed  from  the  time  that 
irrigation  begins,  for  the  rising  water  will  bring  alkali  to  the 
surface  if  any  is  available  in  the  soil,  and  the  longer  this  accumu- 
lates, the  longer  it  will  require  to  reclaim  the  lands  and  the  greater 
will  be  the  expense  thereof.  The  first  surface  evidence  of  a 
dangerous  rise  of  ground  water  may  be  a  temporary  increase  in 
crop  production  induced  by  the  abundant  and  constant  water 
supply  not  yet  excessive.  Numerous  cases  have  occurred 
where  the  rising  water  table  has  produced  large  crops,  and  the 
continuing  rise  as  the  crops  matured  has  so  softened  the  ground 
as  to  render  it  too  boggy  to  permit  machinery  to  harvest  the 
crop.  Usually,  however,  the  progress  is  much  slower  than  this. 
In  order  to  have  proper  warning  of  the  approach  of  dangerous 
seepage,  it  is  necessary  to  keep  close  observation  on  the  position 
of  the  ground  water  by  means  of  wells  located  at  suitable  inter- 
vals over  the  irrigated  tract.  It  is  usually  found  that  there  is  an 
annual  oscillation  of  the  water  level,  which  rises  during  the 
irrigation  season  and  begins  to  decline  slowly  soon  after  the  water 
is  shut  out  of  the  canals.  If  this  decline  is  each  year  back  to 
the  level  at  which  it  began  the  irrigation  season,  and  this  level 
is  not  too  high,  it  may  be  that  the  ground  water  has  ample  escape 
to  neighboring  drainage  lines  through  the  subsoil.  Its  move- 
ments should  be  carefully  watched,  however. 

Fig.  58  shows  the  fluctuation  of  ground  water  in  the  Rio 
Grande  Valley,  New  Mexico,  and  its  relation  to  the  application 
of  water  in  irrigation.  The  ground-water  curve  is  a  composite 
showing  averages  in  twenty  representative  wells  scattered  over 
an  area  of  8500  acres.  The  net  irrigated  area  was  5300  acres,  on 
which  the  average  seasonal  application  was  4.3  feet  in  depth, which 
would  cover  the  gross  area  of  8500  acres  to  a  depth  of  2.7  feet. 

Fig.  59  shows  the  seasonal  fluctuation  and  continual  yearly 
rise  of  ground  water  in  an  irrigated  section  of  the  Boise  Valley, 
Idaho.  Fig.  60  shows  for  another  portion  of  the  Boise  Valley, 
the  fluctuation  of  the  water  table  before  and  after  drainage. 


SIGNS  OF  SEEPAGE 


187 


Moisture  rises  above  the  water  table  by  capillary  attraction, 
the  height  to  which  it  will  thus  rise  varying  from  a  foot  in  sandy 
soil,  to  a  maximum  of  8  feet  in  clay.  When  the  capillary  water 


FIG.  58. — Curve  Showing  Fluctuation  of  Ground  Water  and  Application  of  Irriga- 
tion Water  in  the  Rio  Grande  Valley.     After  Burkholder. 

approaches  the  surface,  evaporation  takes  place,  and  in  coarse 
soil  this  may  prevent  moisture  from  showing  on  the  ground 
until  the  water  table  actually  reaches  the  surface.  When  this 
happens  free  water  will  appear  in  pools,  unless  the  rate  of  seepage 


188 


DRAINAGE 


is  less  than  the  evaporation,  in  which  case  the  free  water  does  not 
appear  although  the  water  table  may  be  practically  at  the 
surface. 

By  taking  frequent  and  careful  observations  of  the  position 
of  ground  water  it  is  possible,  in  most  cases,  to  predict  the  injury 
of  the  land.  These  observations  also  serve  another  useful 
purpose.  An  accurate  knowledge  of  the  ground-water  level 


19/3 


19/4 


J9/ 


/9t7 


to 


18 


ceL 

PX 


FIG.  59. — Curve  Showing  the  Seasonal  Fluctuation  and  Rise  of  Ground  Water 
in  Boise  Valley,  Idaho.     After  Burkholder. 

over  a  considerable  tract  may  indicate  the  movements  of  the 
water,  by  applying  the  simple  rule  that  water  tends  to  flow 
down  hill,  the  slope  of  its  surface  showing  the  direction  of 
flow.  This  knowledge  will  often  show  the  origin  of  much  of 
the  seepage,  and  suggest  means  of  cutting  off  the  supply  by 
providing  intercepting  drains.  Alluvial  streams  with  shallow 
channels  often  feed  the  water  table  as  shown  by  its  response 
to  the  rise  and  fall  of  the  stream.  If  the  subsoil  be  coarse,  this 
response  may  be  quick  and  complete,  but  there  is  always  a  lag 


SIGNS  OF  SEEPAGE 


189 


DEPTH  OF  GROUND  WATER  BELOW  GROUND  SURFACE-FEET 


SNOW  MZLTL 


MAR 
flPff 


do  N 

DEPTH  OF  GROUND  WATER  BTLOW  GROUND 


SURFACE 


-FEET 


FIG.  60. — Curve  Showing  Rise  of  Ground  Water  before  Construction  of  Drains  and 
Effect  of  Drains  at  Considerable  Distance  in  Lowering  and  Keeping  it  Below 
the  Danger  Point.  Record  from  a  well  in  a  drained  district  of  the  Boise  Valley, 
Idaho. 


190  DRAINAGE 

in  time  and  elevation.  That  is,  a  water  table  controlled  by  a 
stream  never  reaches  so  high  a  maximum  elevation  as  the  stream, 
and  reaches  its  culmination  at  a  later  date  than  that  of  the 
stream.  Where  this  maximum  is  so  high  as  to  injure  vegeta- 
tion, it  may  be  necessary  to  install  an  intercepting  drain  near 
and  parallel  to  the  river.  The  same  conditions  are  sometimes 
fulfilled  by  a  canal.  In  fact  the  canals  and  laterals  always 
contribute  a  considerable  portion  of  the  seepage  water  unless 
they  are  lined  with  concrete,  and  where  water  users  are  rea- 
sonably careful  in  the  application  of  the  water  in  irrigation,  the 
canals  and  laterals  in  open  soils  may  contribute  the  major  part 
of  the  seepage  water.  On  the  other  hand,  if  water  is  lavishly 
applied  in  irrigation,  its  contribution  to  the  ground  water  may 
greatly  exceed  the  seepage  from  canals.  It  is  important  to 
ascertain  the  source  of  seepage  water. 

Where  the  soil  is  fine-grained  and  the  water  table  remains 
permanently  4  to  6  feet  below  the  surface,  the  capillary  action 
may  keep  the  soil  moist  in  the  root  zone,  and  good  crops  may 
be  produced  by  means  of  the  ground  moisture  without  surface 
irrigation.  If  the  soil  contains  injurious  salts,  however,  the 
constant  rise  of  water  from  below  and  its  evaporation  from  the 
surface  will  accumulate  those  salts  at  or  near  the  surface  in  the 
soil  occupied  by  plant  roots,  gradually  injure  the  soil,  and 
eventually  make  it  perhaps  entirely  barren. 

The  rise  of  alkali  is  sometimes  the  most  serious  phase  of  the 
seepage  problem.  In  an  arid  region  nearly  all  except  very 
coarse  soils  contain  alkaline  salts  and  a  high  water  table  is  sure 
to  bring  these  toward  the  surface.  If  the  salts  are  abundant 
the  destruction  of  fertility  may  follow  closely  after  the  rise  of 
the  seepage,  and  accumulate  in  the  upper  strata  of  soil  in  such 
quantity  as  to  make  the  reclamation  of  the  land  a  long  and 
expensive  process. 

The  remedy  is  to  provide  drainage  followed  by  irrigation. 
By  the  former  the  water  table  is  lowered,  and  the  irrigation 
water  applied  to  the  surface  and  descending  to  the  water  table 
is  carried  off  through  the  drains.  In  this  journey  downward 
through  the  soil  it  carries  the  alkali  in  solution,  and  it  is  dis- 


CLASSIFICATION  OF  DRAINS  191 

charged  through  the  drains.  The  effort,  therefore,  must  be  to 
reverse  the  upward  movement  of  water,  and  produce  conditions 
by  which  it  will  move  from  the  surface  downward,  carrying 
the  salts  with  it. 

2.  Classification  of  Drains. — With  respect  to  their  functions, 
drains  may  be  divided  into  two  classes: 

1.  Relief  drains,  or  those  furnishing  ready  escape  for  ground 
water  to  the  most  available  natural  drainage  line,  in  order  to 
lower  the  water  table.     They  are  generally  built  on  the  lowest 
available  ground. 

2.  Intercepting  drains,  or  those  designed  to  intercept  seepage 
waters  between   their  source  and   the  lands  to  be  protected. 
They  are  often  built  on  higher  ground  than  the  land  they  are 
designed  to  protect,  but  may  also  serve  as  relief  drains  for  the 
lands  above  them. 

These  two  classes  of  drains  are  by  no  means  distinct,  and  the 
two  functions  are  often  combined  to  some  extent  in  both. 
With  respect  to  their  form,  drains  are  of  two  classes: 

1.  Open  drains  are  those  designed  to  act  as  open  channels, 
to  traverse  the  water  table  and  conduct  the  surplus  water  away. 

2.  Closed  drains  consist  of  tiles  laid  end  to  end  in  a  channel 
in  the  water  table  and  covered  with  earth,  so  that  farming  or 
other  operations  can  proceed  over  the  ground  without  disturbing 
the  action  of  the  drains. 

Where  they  will  answer  the  purpose,  closed  drains  are  of 
course  preferable,  but  their  use  is  restricted  by  their  limited 
capacity  and  their  cost.  Where  the  slope  of  the  country  limits 
the  grade  available  for  the  drain  to  a  very  moderate  amount, 
the  tile  drain,  restricted  by  the  size  of  the  tile,  carries  only  a 
small  amount  of  water,  unless  the  tile  be  made  very  large. 
The  sizes  most  commonly  used  as  main  drains  are  10  inches 
and  12  inches  in  diameter,  but  larger  sizes  up  to  18  inches  in 
diameter  are  sometimes  employed.  Above  18  inches  in  diam- 
eter the  standard  tile  sometimes  fails  under  the  overburden 
of  10  or  12  feet  of  soil,  and  larger  sizes  than  18  inches  are  seldom 
used  except  when  made  extra  heavy  for  this  purpose,  in  which 
case  they  are  very  expensive.  Where  the  capacity  of  an  1 8-inch 


192 


DRAINAGE 


FIG.  61. — Excavating  Trench  for  Tile  Drain,  Montana. 


FIG.  62. — Dragline  Excavator  on  Drainage  Work,  Idaho. 


DESIGN  OF  A   DRAINAGE  SYSTEM  193 

tile  is  insufficient,  it  is  generally  best  to  build  an  open  drain, 
if  practicable. 

3.  Design  of  a  Drainage  System. — The  work  of  designing 
such  a  system  of  drains  as  to  remove  the  menace  of  a  high 
water  table  and  of  rising  alkali,  and  to  leach  from  the  upper 
strata  of  soil  the  accumulations  of  alkali,  in  the  most  effective 
and  economical  manner,  is  generally  complicated,  and  requires 
long  and  close  study  of  the  positions  and  movements  of  both 
surface    and    ground   water    over    several    years.     Moreover, 
this  study  must  continue  until  the  construction  of  the  drainage 
system  has  been  practically  completed,  so  as  to  note  the  effect 
of  drains  after  they  are  in  service,  and  correct    any  errors  of 
assumption  that  may  have  been  involved  in  the  original  plan. 
Every  such  plan  should  therefore  be  considered  tentative,  and 
subject  to  modifications  as  the  work  progresses. 

4.  Location  of  Drains. — To  decide  the  position  and  direction 
of  the  drains  to  be  built,  it  is  important  to  know  the  various 
sources  of  the  seepage  water,  and  also  to  know  the  surface 
topography  and  underground  structure  of  the  land  to  be  drained. 

In  the  treatment  of  underground  waters,  page  45,  it  is  shown 
that  the  flow  of  percolating  water  varies  with  the  slope  of  its 
surface.  Also  that  the  movement  of  water  on  a  given  grade 
is  many  times  more  rapid  through  sand  and  gravel  than  through 
clay  or  loam  having  smaller  openings  between  the  particles. 
Hence,  if  a  drain  be  located  entirely  in  a  fine-grained  soil  like 
clay,  it  can  lower  the  ground  water  only  a  very  short  distance 
back  from  the  drain;  for  no  considerable  quantity  of  water 
can  travel  through  the  clay  soil  except  on  a  steep  grade, 
and  this  brings  the  gradient  quickly  to  the  level  of  the  water 
table. 

Therefore,  if  a  drain  is  to  be  effective,  it  is  necessary  that  it 
shall  tap  a  stratum  of  sand  or  gravel,  or  at  least  some  medium 
through  which  water  can  travel  with  reasonable  velocity  on  a 
slight  gradient.  It  frequently  happens  that  a  clay  or  loam 
soil  needing  drainage  extends  to  a  depth  too  great  for  a  drainage 
ditch,  and  although  the  water  table  may  stand  several  feet 
above  the  bottom  of  the  ditch,  it  will  drain  only  a  few  rods 


194  DRAINAGE 

on  each  side  owing  to  the  steep  gradient  maintained  by  the 
percolating  waters  in  the  tight  soil. 

In  such  case,  relief  is  often  found  by  boring  wells  at  frequent 
intervals  in  the  bottom  of  the  drain  until  a  coarser  stratum  is 
tapped,  and  in  these  wells  the  water  rises  from  the  open  stratum 
into  the  drain  and  flows  away.  This  draws  on  the  ground 
water  from  a  distance,  and  lowers  the  water  table  accordingly. 
Whenever  such  an  open  stratum  is  situated  under  an  irrigated 
region,  it  receives  the  gravity  water  from  the  soil  above,  and 
conducts  it  down  the  slope  frequently  under  tighter  soils,  and 
having  insufficient  outlet  for  all  the  water  it  can  carry,  accumu- 
lates pressure  equal  to  the  hydrostatic  head  of  its  source  of  supply 
minus  the  loss  of  head  due  to  friction.  Acting  under  this  head, 
it  percolates  upward  through  the  overlying  clay  and  loam  and 
waterlogs  the  land,  which  may  not  have  been  irrigated  at  all. 

This  roughly  describes  many  artesian  basins,  which  are 
located  in  "  cienegas,"  or  swamps  formed  in  this  manner.  The 
hydrostatic  head  may  be  insufficient  to  bring  the  water  to  the 
surface  of  the  ground  but  ample  to  cause  it  to  flow  into  the 
bottom  of  a  drain  if  a  well  be  provided  as  an  outlet. 

The  foregoing  illustrates  the  need  of  a  thorough  knowledge 
of  the  subterranean  structure  of  the  country  to  be  drained, 
in  order  that  the  drains  may  be  so  located  as  to  take  advantage 
of  water-bearing  materials  that  may  be  available  to  a  properly 
located  drain. 

It  is  important  to  build  closed  drains  on  as  steep  a  grade  as 
possible  in  order  to  increase  their  discharge  capacity  and  to 
keep  them  clear  of  detritus.  Whether  a  drain  be  open  or  closed 
it  is  usually  desirable  to  give  it  all  the  grade  available.  In  the 
case  of  the  open  drain,  a  good  velocity  tends  to  keep  it  scoured 
out,  and  to  prevent  the  growth  of  aquatic  plants  which  are  the 
bane  of  drainage  ditches.  A  sluggish  velocity  not  only  encour- 
ages aquatic  growth,  but  it  promotes  clogging  by  other  means. 
Tumble  weeds  often  blow  into  the  ditches,  forming  shoals  where 
weeds  can  start,  and  sand  or  silt,  either  from  dust  storms  or 
caving  banks,  accumulate  in  the  ditches  if  the  velocity  be  low, 
whereas  a  swifter  current  would  carry  out  both  weeds  and  silt. 


DEPTH  195 

The  small  quantity  of  water  usually  carried  by  a  drain  and 
its  rough  perimeter  make  it  seldom  possible  to  give  it  grade 
enough  to  permit  destructive  erosion,  and  for  these  reasons  it 
should  generally  be  given  all  the  grade  available. 

For  the  same  reasons  it  is  desirable  to  avoid  abrupt  turns 
in  the  alignment  of  the  ditch,  and  to  avoid  inverted  siphons, 
and  to  give  necessary  culverts  liberal  openings,  and  in  all  respects 
to  avoid  sacrificing  grade,  or  introducing  structures  which  may 
promote  obstruction  by  sand  or  floating  debris. 

To  obtain  the  requisite  grade  for  the  ditches  it  is  generally 
necessary  to  build  them  in  the  direction  of  the  greatest  slope 
of  the  country. 

5.  Depth. — The  ground  water  on  irrigated  land  should  be 
kept  5  feet  or  more  below  the  surface  of  the  ground.     To  accom- 
plish this  the  bottoms  of  drainage  ditches  must  be  considerably 
lower,  in  order  to  make  allowance  for  three  principal  factors: 

1.  The  depth  of  water  in  the  ditch  when  in  service,  which 
deducts  that  much  from  its  drawing  depth. 

2.  The  gradient  which  the  water  table  must  assume  to  dis- 
charge its  surplus  water. 

3.  The  inevitable  decrease  in  depth   of  the  ditch  due  to 
sloughing  and  accumulation  of  detritus. 

It  often  occurs  that  in  excavating  a  drain  sand  is  encountered 
below  the  water  table,  which  under  the  influence  of  inflowing 
water  oozes  into  the  ditch,  and  it  becomes  impossible  to  excavate 
to  the  required  depth  without  holding  the  banks  by  artificial 
means.  This  is  the  only  remedy  where  tile  drains  are  being 
placed,  and  greatly  retards  the  work  and  increases  the  expense. 

Where  such  material  is  encountered  in  constructing  an  open 
drain,  the  best  plan  is  to  make  the  ditch  as  deep  as  practicable, 
and  to  go  over  it  again  a  few  weeks  or  months  later.  In  the 
meantime  the  water  table  will  have  been  lowered  by  the  drain, 
and  it  becomes  possible  to  make  the  drain  considerably  deeper, 
and  perhaps  deep  enough,  although  sometimes  a  third  effort 
may  be  necessary. 

6.  Capacity. — One    of    the    most   difficult   problems    to    be 
solved  in  designing  a  drain  is  to  determine  the  necessary  capac- 


196  DRAINAGE 

ity  which  depends  of  course  on  the  amount  of  water  to  be 
removed.  No  general  rule  can  be  given  as  a  safe  guide  to  the 
solution  of  this  question.  Some  waterlogged  lands  yield  very 
little  water  to  drainage  works.  In  other  cases,  where  the  soil 
is  open  where  seepage  from  canals  is  large,  and  water  is  lavishly 
applied  in  irrigation,  leading  to  heavy  accretions  to  ground 
water,  the  land  may  discharge  into  the  drains  more  than  half  of 
the  water  brought  to  it  by  canals.  These  conditions,  moreover, 
may  not  be  permanent.  Canals  which  at  first  lose  heavily  by 
seepage  may  and  often  do  improve  with  age  by  silting  their 
channels,  or  they  may  be  lined  in  the  worst  places  to  save  water. 
Irrigators  who  apply  water  lavishly  at  first  may  learn  the 
folly  of  this  practice  and  use  water  more  sparingly. 

All  these  conditions  and  possibilities  must  be  taken  into 
account  in  estimating  the  capacity  of  the  drains.  In  the  case  of 
the  open  drain,  which  is  sure  to  deteriorate,  it  is  safe  to  make  its 
capacity  liberal  and  let  it  suffer  deterioration  to  the  necessary 
capacity,  thus  saving  in  maintenance  costs.  If  provision  is 
made  in  advance  for  future  enlargement  this  is  easily  accom- 
plished with  open  drains,  so  that  foreknowledge  is  not  absolutely 
essential. 

Not  so  with  closed  drains.  If  the  tile  is  not  large  enough  to 
discharge  the  necessary  water,  it  cannot  be  enlarged  without 
entirely  rebuilding  the  drain.  If  it  is  too  large  considerable 
extra  expense  is  wasted,  but  as  this  is  much  less  serious  than  if 
too  small,  it  is  best  to  make  the  capacity  liberal. 

The  bottom  width  of  an  open  drain  should  be  fixed  according 
to  the  required  capacity  with  due  allowance  to  rough  construc- 
tion by  machinery  so  that  its  coefficient  of  friction  is  large.  A 
factor  of  roughness  in  the  Kutter  formula,  #  =  .03,  is  about  an 
average  for  new  ditches,  but  to  preserve  such  a  factor  the  main- 
tenance must  be  fairly  well  cared  for. 

7.  Form  of  Tile. — The  best  form  of  tile  used  for  drainage 
purposes  is  the  vitrified  clay  tile,  cylindrical,  without  the  bell 
mouth  employed  for  sewers.  These  tiles  are  laid  end  to  end  as 
close  as  possible,  and  a  strip  of  tar  paper  3  inches  wide,  with  a 
length  one-half  the  circumference  of  the  pipe,  is  laid  over  each 


MANHOLES  197 

joint  to  prevent  the  entrance  of  sand  which  might  clog  the  tile. 
The  water  can  then  enter  the  joints  below  the  horizontal 
diameter. 

A  board  of  a  width  nearly  or  quite  as  great  as  the  diameter 
of  the  tile  should  be  laid  in  the  bottom  of  the  trench  to  keep 
the  tiles  from  settling  out  of  line.  As  the  tiles  are  laid,  it  is 
well  to  pack  some  earth  against  them  to  hold  them  in  line 
horizontally  until  the  trench  is  backfilled. 

If  the  drain  is  laid  in  quicksand  it  is  best  to  use  a  better 
foundation  than  the  board  above  described.  This  may  con- 
sist of  two  pieces  of  2  inch  by  4  inch  lumber  spaced  parallel 
with  a  space  between  about  half  the  diameter  of  the  tile,  and 
nailed  together  by  three  or  four  cross-pieces,  forming  a  ladder. 
This  is  laid  in  the  trench  with  the  cross-pieces  underneath,  and 
the  tiles  are  fitted  into  the  space  between  the  sides  of  the  ladder 
which  holds  them  in  place  both  horizontally  and  vertically. 

When  convenient  it  is  best  to  allow  the  tiles  to  remain  in 
place  a  few  days  before  backfilling,  and  to  inspect  them  to  see 
that  they  have  not  become  displaced. 

The  backfilling  should  be  performed  carefully  so  as  not  to 
displace  the  tiles,  and  where  a  choice  is  possible,  it  is  well  to 
place  the  coarsest  material  available  next  to  the  tiles.  Any  tile 
drain  is  improved  by  placing  gravel  next  to  the  tile  before  back- 
filling. 

8.  Manholes. — At  intervals  of  about  100  feet  it  is  advisable 
to  provide  an  open  well  to  serve  as  a  manhole.  This  can  be  lined 
with  lumber,  and  the  drain  from  above  can  discharge  into  the 
well,  and  the  lower  drain  carry  the  water  away.  These  wells 
have  several  uses.  They  may  serve  as  sand  traps,  to  catch 
any  sand  that  may  be  traveling  down  the  drain  which  might 
clog  it.  For  this  purpose,  the  bottom  of  the  well  should  be 
2  or  3  feet  below  the  grade  of  the  drain,  and  should  be  kept 
cleaned  out.  The  well  should  be  at  least  3  feet  in  diameter 
so  as  to  permit  a  man  to  work  in  it.  Such  wells  serve  to  show 
whether  the  drain  is  operating  under  a  hydrostatic  head,  in 
which  case  the  water  will  stand  in  the  well  higher  than  the  top 
of  the  tile.  Such  a  well  should  be  placed  at  any  point  where 


198  DRAINAGE 

the  grade  of  a  drain  changes  in  such  a  way  as  to  check  the 
velocity  of  the  drainage  water,  for  at  and  below  such  critical 
points  there  is  a  tendency  to  deposit  sand,  and  it  is  desirable  to 
remove  this  by  means  of  the  well. 

In  case  of  a  broken  tile  or  other  derangement  of  the  drain, 
frequent  manholes  assist  in  locating  the  trouble.  Where  the 
slope  of  the  ground  changes,  making  it  necessary  to  reduce  the 
slope  on  which  the  drain  is  laid,  the  size  of  the  tile  should  be 
increased  so  as  to  give  it  at  least  a  greater  capacity  than  the 
portion  of  the  drain  above.  Such  a  change  is  most  conveniently 
made  at  a  manhole.  The  manhole  or  well  is  a  convenient  loca- 
tion for  a  weir  to  measure  the  discharge  of  the  drain,  a  record 
of  which  should  be  carefully  kept,  as  it  is  of  great  value  in 
denoting  the  action  of  the  drain,  and  its  effect  on  the  ground 
water. 

9.  Wooden  Drains. — Where    earthen    drain    pipe    is    very 
expensive  on  account  of  freight  charges,  and  lumber  can  be 
cheaply  obtained  locally,  wood  has  been  used  instead  of  clay 
tile.     The  economy  of  this  is  generally  doubtful,  unless  it  is  cer- 
tain that  the  wood  will  be  continuously  saturated.     Otherwise, 
its  early  decay  will  require  its  replacement  so  soon  as  nearly  or 
quite  to  neutralize  its  advantage  in  low  first  cost.     Where  wood 
is  used,  it  may  be  formed  into  a  square  box,  of  such  length  as 
convenient,  and  if  the  box  is  large,  the  top  should  be  laid  with 
the  grain  transverse  to  the  length  of  the  drain,  to  give  it  the 
required   strength.     Each   board   forming   the    top   should   be 
slightly  gained  at  each  end,  so  that  it  will  fit  to  the  sides,  and 
prevent  their  collapse  from  lateral  pressure.     A  similar  precau- 
tion may  be  taken  with  the  bottom,  so  that  little  dependence 
need  be  placed  upon  nails  to  hold  the  parts  of  the  box  in  place. 
The  bottom  should  break  joints  with  the  sides,  to  preserve  the 
alignment. 

10.  Cement  Drains. — In    some  cases   cement  pipe  may  be 
cheaper  than  clay  tile,  and  it  answers  the  purpose  well  unless 
alkali  is  present.     If  the   soil  contains  much  alkali,  especially 
sulphates,   there  is   danger  of   the   cement  pipe  disintegrating 
especially  if  not  running  full  continuously. 


CEMENT  DRAINS  199 

The  U.  S.  Bureau  of  Standards  in  cooperation  with  the 
Reclamation  Service  has  made  a  series  of  tests  on  the  use  of 
cement  pipe  as  drain  tile,  exposed  to  soils  containing  alkaline 
salts,  and  draws  these  conclusions: 

1.  The  use  of  cement  tile  in  soils  containing  alkali  salts  in 
large  quantities  is  experimental. 

2.  Porous  tile  due  to  the  use  of  lean  mixtures  or  relatively 
dry  consistencies  are  subject  to  disintegration. 

3.  Some  dense  tile  are  under  certain  conditions  subject  to 
surface  disintegration. 

4.  Disintegration     is    manifested     by    physical    disruption 
caused  by  the  expansion  resulting  from  the  crystallization  of 
salts  in  the  pores  and  by  softening,   resulting  from  chemical 
action  of  the  solutions  with  the  constituents  of  the  cement. 

5.  While  results  obtained  will  not  permit  of  a  definite  state- 
ment as  to  the  relative  effect  of  the  various  constituents  of  the 
salts,  indications  are  that  the  greater  the  quantity  of  sulphate 
and  magnesium  present  and  the  greater  the  total  concentration 
of  salts  the  greater  will  be  the  disintegrating  effect. 

6.  Tile  made  by  the  process  commonly  used,  which  allows 
the  removal  of  forms  immediately  after  casting,  are  subject  to 
disintegration  where  exposed  to  soils  or  waters  containing  TO  per 
cent  or   more  alkali  salts  similar  in  composition  to  those  en- 
countered in  this  investigation. 

7.  The  hand- tamped  tile  of  plastic  consistency  as  made  in 
this  investigation  are  not  equal  in  quality  to  machine-made  tile 
of  the  same  mixture,  and  they  do  not  resist  alkali  action  as  well. 

8.  Steam-cured   tile   show   no   greater   resistance   to   alkali 
action  than  tile  which  are  cured  by  systematic  sprinkling  with 
water. 

9.  Tile  made  of  sand  cement  have  less  resistance  to  alkali 
action   than   the   tile  made   of   Portland   cement  of  the  same 
proportions. 

10.  The  tar  coating  as  used  is  not  effective  in  preventing  the 
absorption  of  alkali  salts  from  the  soil. 

12.  No  advantage  is  found  in  introducing  ferrous  sulphate 
into  the  cement  mixture. 


200 


DRAINAGE 


If  cement  drain  tile  are  to  be  used  in  alkali  soils  or  waters 
containing  o.i  per  cent  or  more  of  salts  they  should  be  made  of 
good  quality  aggregate  in  proportions  of  not  less  than  one  part 
Portland  cement  to  three  parts  aggregate.  The  consistency 
should  preferably  be  quaking,  which  has  proved  the  most  resist- 
ent  of  all  mixtures  used. 

ii.  Drainage  Works  of  the  U.  S.  Reclamation  Service. 

TABLE  XXVIII.— OPEN  DRAINS 


COST 

Project 

Mites 

Cu.  Yds. 

Acres 

Per 
Mile 

Per 
Cu.  Yd. 

Per 
Acre 

Boise  
Alinidoka 

130.0 
108  o 

5,533,002 
3,367018 

64,680 
72,000 

$5281 
6143 

$-067 
ill 

$10.58 
0    22 

Yuma  
North  Platte.  .  .  . 
Carlsbad  

16.8 

23o 
11.7 

375,ooo 
410,640 
292,248 

8,000 
2,900 
4,320 

7650 
4000 
6336 

.250 
.  140 
.255 

I4.OO 
30.00 
17.  2S 

Rio  Grande  
Umatilla  

22.8 
IO.O 

865,300 
225,000 

6,000 
2,000 

8815 
5481 

•115 
•  244 

16.00 
27.40 

Klamath  
Shoshone  
Huntley  

77-5 
13-5 

13  .  2 

972,000 
486,500 
504,150 

17,400 
2,000 
19,400 

3718 
72OO 
7630 

.  2OO 
•174 

•  I5° 

16.50 

26.50 

16.  25 

TABLE  XXIX.— CLOSED  DRAINS 


Project 

8  INCHES 

10  INCHES 

12  INCHES 

Length, 
Feet 

Unit 
Cost 

Length, 
Feet 

Unit 
Cost 

Length, 
Feet 

Unit 
Cost 

Yuma 

I 

Huntley 

11,470 

$0.97 

22,089 
3o50 
15^50 

17,107 
.  89,334 

Si.  37 
i-39 
1.46 
0.98 
1.14 

99,217 
39,838 
4,445 
25,661 
151,428 

$1.44 

1-39 
1.62 
1.04 
i.  20 

North  Platte  
Carlsbad 

Klamath  

Shoshone  

Total  

11,470 

$0.97 

147,330 

$1.27       320,589 

$i-34 

DRAINAGE  WORKS  OF  THE   U.  S.  SERVICE 
TABLE  XXIX.— CLOSED  DRAINS— Continued 


201 


Project 

15  INCHES 

18  AND  20  INCHES 

Total  Cost. 

Length, 
Feet 

Unit 
Cost 

Length, 
Feet 

Unit 
Cost 

Yuma  
Huntley 

5,525 
ioi,935 
31,102 

$1.50 
1  .46 
1-39 

15,400 
13,635 

$I.7I 
i-37 

$34,597 
358,893 
126,104 
44,013 
43,452 
460,940 

North  Platte  

Carlsbad 

Klamath  

Shoshone.    .  . 

90,275 

i-3i 

60,586 

1.44 

Total       

228,837 

sSi-45 

89,621 

$1.50 

Remark:     Average  cost  of  closed  drains  in  table  $1.35  per  foot. 

REFERENCES  FOR  CHAPTER  XII 

KING,  F.  H.     Irrigation  and  Drainage.     The  Macmillan  Company,  New  York. 
DAVIS,  ARTHUR  P.     Irrigation  Works  Constructed  by  the  United  States.     John 

Wiley  &  Sons,  New  York. 
HART,  R.  A.     Drainage  of  Irrigated  Land.     Bulletin  No.  190,  Office  of  Experiment 

Stations. 
TANNATT  AND   KNEALE.     Seepage  and  Drainage.     Bulletin  No.    76,   Montana 

Agricultural  College,  Bozeman,  Montana. 
Engineering  Record.     Cost  of  Excavating  Drainage  Ditches  with  Steam  and 

Electric  Machines.     Vol.  LXX,  No.  26. 
YARNELL,  D.  L.    Trenching  Machinery  used  for  Construction  of  Trenches  for 

Tile  Drains. 
ELLIOTT,  C.  G.     Drainage  of  Farm  Lands.     Farmers'  Bulletin  No.   187,  U.  S. 

Office  of  Experiment  Stations. 
CRONHOLM,  F.  N.     Drainage  System  for  North  Side  Minidoka  Irrigation  Project. 

Engineering  Record,  April  15,  1914. 
MURPHY,  D.  W.     Drainage  of  Shoshone  Irrigation  Project.     Engineering  Record, 

June  6,  1914. 
BURKHOLDER,  J.  L      Conserve  your  Little  Drop  of  Water  and  Help  Keep  Down 

the  Peak.    Reclamation  Record,  December,  1917. 


CHAPTER  XIII 
CANALS  AND  LATERALS 

i.  Capacity. — To  decide  upon  the  necessary  capacity  of  an 
irrigation  canal,  it  is  necessary  to  know  approximately  the  three 
main  factors  which  control : 

1.  The  acreage  of  land  to  be  served. 

2.  The  duty  of  water. 

3.  Seepage  losses  to  be  expected. 

Unless  great  care  is  exercised  in  considering  each  of  these  factors 
and  conservative  estimates  are  made,  much  danger  exists  of 
serious  error  in  the  determination  of  each  one.  The  principles 
upon  which  decisions  must  be  based  are  given  in  the  preceding 
pages. 

The  data  for  such  decisions  are  not  accurately  determinable 
in  advance,  and  careful  consideration  must  be  given  to  the 
margin  of  safety  to  be  allowed  to  guard  against  unavoidable 
errors  both  in  the  data  and  the  conclusions  drawn  from  them. 

Having  determined  the  three  factors  above  listed,  the  capacity 
of  the  canal  may  be  conveniently  found  by  the  following  formula: 
Let  c  =  capacity  required  in  cubic  feet  per  second; 
a  =  area  to  be  irrigated  in  acres ; 
d  =  average  depth  of  water  in  feet  required  on  the  land 

in  the  15  days  period  of  maximum  use; 
p  =  percentage  of  loss  by  seepage  and  evaporation. 
Remembering  that  a  stream  flowing  at  the  rate  of  i  cubic  foot 
per  second  carries  29.7  acre-feet  of  water  in  15  days,  we  have 

ad  I         p\ 
c  = i-     -I (i) 

29.  7 \       loo/ 

Example :  Required  the  capacity  at  head  of  main  canal,  necessary 
to  serve  10,000  acres  of  land,  where  the  maximum  requirement 

202 


CAPACITY  203 

of  crops  for  a  1 5-day  period  is  an  average  depth  over  the 
irrigable  area  of  .3  foot,  and  the  losses  in  canals  when  operating 
at  full  capacity  will  be  20  per  cent  of  the  water  diverted,  or 

a  =10,000, 
d--3, 

p  =  20. 

Then  by  (i) 

.3X10,000     3,000 

——5 —  = 7  =  126.26. 

29.7X80      23.76 

In  the  design  of  the  canal  some  excess  capacity  should  be  pro- 
vided to  allow  for  possible  errors  in  the  assumptions  which  must 
be  made  from  uncertain  data.  Excess  capacity  is  not  wasted, 
for  a  canal  begins  to  deteriorate  as  soon  as  built.  Wind,  rain, 
frost  and  the  trampling  of  animals  work  the  banks  down  and 
tend  to  fill  the  canal  with  dirt  and  trash,  and  the  capacity  thus 
gradually  diminishes  unless  restored  by  annual  repairs.  This 
is  especially  true  where  the  water  contains  much  silt.  In  such 
cases,  it  is  always  best  to  provide  considerable  excess  capacity 
so  that  a  substantial  lining  of  silt  may  be  allowed  to  remain 
in  the  canal,  as  this  not  only  saves  the  cost  of  removing  the 
same,  but  improves  the  canal  by  rendering  it  less  pervious  and 
decreasing  its  coefficient  of  friction.  Unless  such  excess  is 
allowed,  especially  in  laterals,  the  silting  may  so  decrease  the 
capacity  as  to  make  it  impossible  to  deliver  sufficient  water 
for  the  needs  of  the  crops  while  it  may  be  impossible  to  close 
the  canal  for  cleaning  without  heavy  loss  to  the  farmers  requir- 
ing the  water.  The  requirement  for  a  large  excess  capacity 
is  most  advisable  on  the  small  laterals,  where  the  tendency 
to  deposit  silt  is  often  great,  and  where  the  cost  of  constructing 
such  excess  is  generally  small.  It  may  sometimes  even  be 
advisable  where  water  is  very  silty  to  build  the  laterals  of  two 
or  three  times  the  capacity  absolutely  necessary  for  service, 
and  allow  them  to  accumulate  silt  until  the  capacity  diminishes 
to  that  required,  as  this  is  both  better  and  cheaper  than  frequent 
removal  of  small  quantities  of  silt.  Larger  quantities  can  be 
removed  at  a  lower  unit  cost. 


204 


CANALS  AND  LATERLAS 


N  =  0.2o  V=2.95 

S=.OC017  Q=1418      ^ 


-45;5- 


N  =  0.25 
S  =.00016 


V  =  2.87 
Q  =  1415 


Scale  of  Feet 
15  0  15  30 


45 


FIG.  63. — Cross-sections  of  Interstate  Canal,  North  Platte  Valley,  Nebraska. 


DESIGN  205 

2.  Design. — The  problems  of  canal  design  and  location 
may  be  divided  into  two  general  cases: 

1.  Cases  in  which  the  water  supply  is  greater  than  the  avail- 
able land,  making  it  necessary  to  give  the  canal  the  least  practi- 
cable grade,  in  order  to  command  by  gravity  canal  the  maximum 
area  of  land,  or  to  reach  a  sufficient  area  without  undue  length 
of  canal. 

2.  Cases  in  which  the  area  of  good  land  readily  commanded 
by  the  canal  is  in  excess  of  the  available  water  supply,  or  the 
configuration    of    the   country  is   such   that  abundant  fall  is 
available. 

Where  it  is  very  desirable  to  save  grade,  as  in  case  i,  the 
canal  should  be  given  a  section  such  that  it  will  have  a  large 
hydraulic  radius,  and  hence  have  a  reasonably  high  velocity 
on  the  gentle  grade  given.  In  a  rectangular  channel,  the 
hydraulic  radius,  and  consequently  the  velocity,  is  a  maximum 
when  the  depth  of  water  is  one-half  the  width.  A  rough  rule 
for  trapezoidal  channels  is  that  the  depth  should  be  about  half 
the  bottom  width,  to  give  maximum  capacity,  but  this  rule  is 
generally  modified  by  considerations  of  economy  of  construction 
and  operation,  which  require  less  depth  and  greater  width, 
except  on  side  hills;  especially  is  this  true  of  large  canals.  The 
advisable  section  lies  somewhere  between  the  cheapest  section 
and  the  one  affording  the  highest  velocity.  It  must  be  deter- 
mined in  each  individual  case  by  a  consideration  of  all  details 
affecting  the  problem,  such  as  the  value  of  the  land  to  be  gained, . 
and  whether  the  water  carries  silt,  making  a  good  velocity 
necessary  to  prevent  silting  of  canals. 

In  the  second  case  cited  where  ample  grade  is  available, 
it  is  generally  desirable  to  give  the  canal  as  much  velocity  as 
the  earth  will  stand  without  erosion,  and  where  rock,  gravel,  or 
hardpan  must  be  excavated  economy  may  often  be  promoted 
by  increasing  the  grade  and  velocity  of  the  canal  so  as  to  reduce 
the  cross-section  and  thus  save  excavation.  It  should  be  remem- 
bered, however,  that  in  such  places  there  is  often  danger  of 
seepage  through  the  seams  of  the  rock  or  gravel,  and  where 
velocities  are  high  it  becomes  impossible  to  close  such  crevices 


206 


CANALS  AND  LATERALS 


by  the  process  of  silting,  and  it  may  be  necessary  to  line  the 
section  with  concrete,  in  which  case  a  further  increase  of  velocity 
due  to  the  greater  smoothness  is  secured,  and  the  cross-section 
may  then  be  further  reduced.  In  fact  where  it  is  necessary 


FIG.  64. — Canal  Cross-sections  for  Varying  Bed-widths. 

to  cut  through  rock  for  any  great  distance  the  cost  may  often 
be  reduced  by  lining  the  cut  with  concrete,  which  so  reduces  the 
friction  that  the  higher  velocity  permits  a  reduction  in  cross- 
section  sufficient  to  save  the  cost  of  lining.  This  is  especially 
the  case  with  deep  cuts  or  side  hill  location. 


SIDELONG  GROUND-W.L.  ABOVE  G.L. 

6'0" 

•vr  46 


GTround 


May  require  Puddle  Wall 
as  indicated 


SOD  REV.EJMENTS 
WITHOUT  BERMS-W.L  BELOW  G.L. 
W.L-- 


Level 


WITH  BERMS-W..L.  BELOW  G.L. 


Ground 


FIG.  65. — Various  Canal  Cross-sections. 

In  the  construction  of  earthen  canals,  economy  requires 
that  embankments  be  utilized  to  assist  in  forming  the  waterway, 
and  the  most  economical  form  is  that  in  which  the  excavation 
is  sufficient  to  form  the  embankment  with  a  small  allowance 
for  wastage  and  shrinkage,  usually  assumed  about  10  per  cent 
for  small  canals,  and  5  per  cent  for  large  ones.  On  level  or  gently 


DESIGN  207 

sloping  ground,  a  wide  and  shallow  canal  in  which  excavation 
equals  embankment  is,  for  a  given  cross-section  cheaper  than  a 
narrower  and  deeper  one.  It  has  a  greater  perimeter  and  less 
hydraulic  radius,  and  hence  requires  more  grade  for  a  given 
velocity,  but  if  this  is  available  a  wide  canal  may  be  advisable. 
This,  however,  introduces  another  element  that  must  be  studied. 
In  general  the  seepage  from  a  canal  is  roughly  proportional 
to  the  wetted  area,  and  therefore  in  uniform  material  more 
seepage  may  be  expected  from  a  wide  than  from  a  narrow  canal. 
If  the  material  is  naturally  porous,  this  result  may  be  emphasized, 


FIG.  66. — Rock  Cross-section,  Turlock  Canal. 

for  in  such  cases,  an  artificial  bank  can  often  be  made  tighter 
than  the  natural  material,  and  the  narrow  canal  with  its  greater 
proportion  of  embankment  may  be  tighter  than  the  wide  one. 
Local  conditions,  however,  may  greatly  modify  this  result. 
It  often  happens  that  the  upper  soil  which  contains  loam  is 
better  adapted  for  making  a  tight  waterway  than  that  which 
underlies  it,  and  the  narrow  canal  with  its  deeper  cut  may 
expose  a  coarse  gravelly  subsoil,  into  which  seepage  may  be  so 
rapid  as  to  overbalance  the  decreased  surface  of  percolation. 
For  these  reasons  it  may  be  advisable  to  adopt  varying  types  of 
cross-section  on  different  parts  of  the  same  canal  in  accordance 
with  the  soil  and  subsoil  conditions. 

On  nearly  level  ground  a  given  canal  cross-section  requires 
less  excavation  if  wide  and  shallow  than  if  narrow  and  deep. 


208 


CANALS  AND  LATERALS 


A  given  amount  of  material  is  required  for  the  formation  of 
banks  of  a  certain  height,  and  the  wider  apart  these  are  placed 
the  greater  the  cross-section  of  the  waterway.  Where  the 
location  is  on  a  side-hill  slope,  this  rule  does  not  obtain,  as  the 
difference  in  elevation  between  the  two  sides  of  the  canal  requires 
a  high  bank  on  one  side  and  none  on  the  other.  Further  widen- 
ing requires  a  still  higher  bank  on  the  lower  side,  and  a  heavier 
cut  on  the  upper  side,  so  that  on  hillsides,  the  narrow,  deep 
section  is  generally  cheaper,  and  this  is  the  more  emphatic  as  the 
hillside  becomes  steeper.  Where  the  side  hillside  slope  is  very 
steep,  the  slope  of  the  canal  section  will  intercept  the  surface 


ry  Rubble 


SECTION   IN   ROCK 

«=37.7         P  =  15.4  r=  2.44 

W=.012         s  =.00124        U=7.96 

Q=SCO 

A  B 

FIG.  67. — Rock  Cross-section;  Umatilla  Canal. 


slope  of  the  ground  at  some  distance  above  the  canal,  and  to 
prevent  excessive  cost  it  becomes  necessary  to  make  the  canal 
slopes  as  steep  as  possible  and  in  extreme  cases  to  make  them 
of  the  character  of  a  masonry  retaining  wall.  At  the  same  time 
it  may  be  advisable  to  make  the  lower  bank  of  earth  on  the 
usual  slopes,  giving  rise  to  cases  where  the  two  sides  of  the 
waterway  have  different  slopes.  The  economic  section  will 
depend  also,  to  some  extent,  on  the  character  of  the  material 
to  be  excavated.  In  hard  rock  the  cost  of  excavation  makes 
yardage  predominant,  and  a  lined  channel  is  generally  economi- 
cal. In  open  or  porous  material,  the  area  exposed  to  seepage 
is  important,  and  may  require  the  minimum  attainable  wetted 
perimeter. 


DESIGN  209 

Where  the  water  to  be  carried  is  clear,  and  growth  of  aquatic 
plants  is  to  be  anticipated,  the  deeper  canal  has  advantages, 
because  less  likely  to  permit  the  growth  of  such  plants.  They 
require  bright  sunlight,  and  deep  waters  shade  the  bottom  of 
the  canal  too  much  for  their  fullest  development. 

Large  canals  on  nearly  level  ground  are  sometimes  con- 
structed with  a  berm,  or  level  width  of  natural  ground  between 
the  excavated  channel  and  the  banks.  This  has  the  advantage 
of  affording  a  shallow  section  and  therefore  low  velocity  next 
to  the  banks  and  less  tendency  to  erode  them,  but  this  also 
encourages  the  growth  of  weeds  and  aquatic  plants,  and  the 
provision  of  berms  is  not  usually  advisable  practice. 

The  side  slopes  of  canals  in  earth  should  be  made  somewhat 
flatter  than  the  natural  slope  of  repose  of  the  material,  in  order 
to  add  to  their  stability  and  diminish  their  tendency  to  slough 
and  to  work  down  the  slope.  Slopes  of  two  horizontal  to  one 
vertical  are  common,  and  are  good  practice  in  average  ground. 
Banks  of  sandy  soils  are  sometimes  made  flatter,  and  very  firm 
soils  may  be  left  steeper,  especially  in  cut,  which  may  some- 
times retain  stability  on  steeper  slopes  than  the  same  material 
requires  in  embankment.  In  deep  cuts  economy  demands 
that  the  banks  be  left  as  steep  as  safety  will  permit.  In  loose 
sand  and  gravel  this  is  about  i|  horizontal  to  i  vertical,  being 
very  little  flatter  than  the  angle  of  repose.  Firm  clay  may  stand 
much  steeper  than  this,  as  may  also  indurated  material  of  all 
kinds.  Fairly  firm  rock  will  stand  practically  vertical,  except 
in  very  deep  cuts,  and  between  this  limit  and  the  slope  given  for 
sand,  all  other  materials  find  their  safe  slopes. 

The  top  width  of  canal  banks  should  vary  with  the  size  of  the 
canal.  Where  large  canals  follow  nearly  on  contours,  with 
higher  ground  on  one  side,  and  lower  ground  on  the  other,  the 
upper  bank  may  be  rather  light,  as  its  rupture  will  not  threaten 
serious  damage,  while  the  lower  bank  must  be  made  much 
heavier  to  give  necessary  security  against  disastrous  breaks. 
It  is  generally  advisable  to  make  the  lower  bank  of  a  large  canal 
wide  enough  to  form  a  wagon  road.  This  facilitates  the  patrol 
of  the  canal,  saves  other  land  necessary  for  such  a  road,  and 


210  CANALS  AND  LATERALS 

adds  stability  and  security  to  the  canal.  Such  a  road  should  not 
be  less  than  10  feet  in  width,  and  a  greater  width  is  better, 
especially  in  light  sandy  soil.  Turnouts  for  passing  teams 
should  be  provided,  which  can  be  done  without  extra  expense 
at  points  where  excess  cut  furnishes  considerable  surplus 
material.  The  lower  or  main  bank  should  be  at  least  3  feet 
above  the  water  level  of  the  canal  in  large  canals,  but  may  be 
less  in  small  canals. 

The  lower  bank  of  the  canal  must  be  carefully  built,  and  if  the 
excavated  material  available  for  canal  building  is  coarse,  care 
must  be  taken  to  place  such  fine  material  as  it  contains  on  the 
water  slope,  and  the  coarser  material  on  the  outside.  If  not 
enough  fine  material  is  found  in  the  canal  prism  for  this  purpose, 
it  may  be  necessary  to  haul  clay  or  loam  from  a  distance  for 
this  purpose,  or  in  some  cases  it  may  be  advisable  to  line  with 
concrete.  A  bank  of  coarse  gravel  or  broken  rock  on  a  good 
foundation  is  an  ideal  bank,  provided  the  water  slope  is  made 
practically  impervious  with  clay  or  otherwise. 

Cross-section  with  Subgrade. — In  light  soils  it  has  been  found 
advantageous  to  dig  a  subgrade  i  to  2  feet  below  the  original 
canal  bed.  The  cross-section  gradually  approaches  that  of  the 
ellipse  and  tends  to  keep  the  current  in  the  center  of  the  channel 
and  to  keep  up  its  flow  with  the  least  exposure  to  friction  and 
seepage  when  the  volume  of  water  in  the  canal  is  low.  The 
subgrade  (Fig.  68)  is  given  by  practically  designing  the  canal 
as  if  it  were  to  have  a  trapezoidal  cross-section  with  berm,  and 
then  evening  off  the  slope  by  removing  the  berm  and  contin- 
uing the  slope  from  the  bottom  of  the  canal  toward  the  center. 

It  is  sometimes  necessary  to  locate  a  conduit,  along  a  steep 
hillside,  where  the  material  naturally  lies  about  the  angle  of 
repose,  so  that  the  excavation  of  a  canal  would  so  weaken  its 
support  as  to  cause  such  a  tendency  to  slide  that  the  canal  would 
be  unsafe.  Several  alternatives  are  then  presented. 

1.  To  excavate  a  bench  and  build  a  flume  upon  it.     It  may 
be  that  this  will   too   greatly  weaken  the  hillside,  and  invite 
sliding,  especially  in  the  presence  of  the  water  of  the  canal. 

2.  Without  disturbing  the  natural    material,  build  a  flume 


DESIGN 


211 


on  a  trestle,  elevated  sufficiently  to  permit  rolling  rocks  to  pass 
under.  If  this  flume  is  to  be  of  concrete,  it  would  be  expensive. 
If  of  wood  or  steel,  it  would  be  rather  short  lived. 

3.  A  pipe  may  be  built  and  buried,  leaving  the  slope  in  its 
original  condition.  This  would  be  the  safest,  but  most  ex- 
pensive of  the  solutions,  and  might  be  prohibitive. 


FIG.  68. — Cross-section  of  Galloway  Canal  in  Sand,  showing  Subgrade. 

4.  A  compromise  among  the  above  alternatives  sometimes 
adopted  is  to  excavate  a  bench  and  build  thereon  a  concrete 
flume  with  sufficient  strength  to  support  the  upper  bank  like  a 
retaining  wall,  and  thus  restore  the  support  to  the  slope,  without 
involving  as  heavy  expense  as  the  pipe  in  solution  3. 

The  lined  canal  or  flume  in  the  Tieton  Canyon  of  Washing- 
ton may  be  classed  as  a  case  of  this  kind.  Fig.  70.  This  flume 


FIG.  69. — Typical  Section  of  Lined  Canal. 

is  of  circular  section,  with  a  segment  cut  off  the  upper  part, 
and  concrete  chords  provided  to  restore  its  rigidity.  The  cir- 
cular section  and  the  chords  were  both  reinforced.  They  were 
manufactured  in  2-foot  sections  in  the  bottom  of  the  canyon, 
where  ample  room  and  materials  were  available,  and  were 
hoisted  to  place  and  joined  in  a  continuous  flume  in  place  by 
cement  joints. 

Where  stretches  of  lined  canal  are  on  a  very  steep  grade  the 
water  assumes  a  correspondingly  high  velocity,  and  measures 
to  destroy  this  velocity  may  be  necessary  at  the  foot  of  the 
steep  grade,  and  it  may  also  be  necessary  to  provide  a  regulator 


212  CANALS  AND  LATERALS 

at  the  upper  end,  to  shut  out  the  water  at  times.  Such  a  com- 
bination is  called  an  inclined  drop,  or  chute.  It  is,  of  course, 
located  at  the  point  where  the  necessary  fall  can  be  compressed 
into  the  shortest  practicable  distance.  It  consists  essen- 
tially of  an  inlet  structure,  a  trough  to  conduct  the  water  down 
the  hill,  and  a  pool  at  the  bottom  to  receive  the  water  and 
destroy  its  c,ccumulated  energy.  The  inlet  structure  forming 
the  transition  is  provided  with  splayed  wing  walls,  and  well 
equipped  with  cut-off  walls  for  the  wing  walls,  floor  and  sides,  to 
prevent  percolation  of  water  along  the  structure.  At  the  lower 
end,  where  the  water  enters  the  trough,  it  is  provided  with  con- 
trol gates.  The  trough  converges  to  a  narrow  channel  a  short 
distance  below  the  gates,  to  correspond  to  the  increased  velocity, 
which  may  reach  about  40  or  50  feet  per  second,  the  section 
again  increasing  as  it  approaches  the  pool  at  the  bottom.  Cut- 
off walls  are  provided  under  the  trough  at  frequent  intervals  to 
prevent  erosion  by  leakage  or  rain  water.  These  are  generally 
i  foot  deep,  except  at  expansion  joints,  where  they  are  deeper. 

3.  Alinement.— Owing  to  its  moderate  velocity,  the  alinement 
requirements  of  canal  location  are  not  so  rigid  as  in  railroad  work. 
Location  upon  the  contour  that  will  keep  the  cut  and  fill  in  ap- 
pr  ximate  balance  is  generally  the  cheapest  per  foot,  but  on 
rolling  ground  this  may  make  the  line  so  crooked  as  to  intro- 
duce excessive  curvature  and  to  increase  the  length  to  such  an 
extent  as  to  actually  increase  the  yardage  excavated,  over  a  less 
tortuous  location.  On  curves  there  is  always  a  tendency  to 
erode  the  bank  on  the  convex  side  of  the  canal  and  unless  the 
velocity  is  very  low  this  must  be  carefully  provided  for.  Where 
the  convex  side  is  an  embankment,  as  when  passing  around 
the  end  of  a  ridge,  it  is  generally  best  to  throw  the  location  into 
cut  in  order  to  resist  the  tendency  to  erode,  and  this  will  also 
eliminate  part  of  the  curvature.  This  will  shorten  the  line,  im- 
prove the  alinement  and  make  a  safer  location,  and  accordingly 
some  increase  of  cost  can  be  justified.  A  great  variety  of  rules 
have  been  suggested  concerning  curvature  limits,  but  these  are 
of  little  value,  as  the  limits  must  be  determined  by  circumstances 
above  discussed.  A  straight  alinement  is  best,  but  curvatures 


A  LI  N  EM  EN  T 


213 


can  be  introduced  to  almost  any  extent  demanded  by  economy, 
and  not  prohibited  by  safety. 

Various  rules  have  been  proposed,  limiting  the  curvature 
to  certain  relations  to  the  width  or  depth  of  the  canal,  but  these 


2-^"corr.  bars 
""-  10  (fig. 


STANDARD   TUNNEL  SHAPE  S.ECTION  D-D 

FIG.  70. — Tunnel  and  Canal  Sections,  Tieton  Main  Canal. 

appear  illogical  as  the  erosion  will  depend  not  so  much  upon  the 
width  nor  the  depth,  as  upon  the  velocity  of  the  water,  next  to 
the  bank.  It  is  true  that  the  larger  the  volume  of  the  flowing 
water,  the  greater  the  difference  between  the  maximum  and  min- 


214  CANALS  AND  LATERALS 

imum  velocities,  and  on  curves  the  maximum  tends  to  approach 
the  bank  on  the  outside  of  the  curve,  and  in  this  way  to  increase 
the  liability  to  erosion.  This  tendency  increases  as  the  curva- 
ture increases,  and  also  as  the  velocity  increases.  Any  rule  for 
curvature  must,  therefore,  recognize  all  these  influences,  the 
greatest  of  which  is  the  velocity.  Different  materials  resist 
erosion  in  differing  degrees,  and  any  rule  fitting  average  earth 
must  be  modified  for  lighter  or  heavier  soils. 

For  average  loam  soils,  the  following  is  a  safe  formula: 

R=V2\/A+40. 

In  the  above  equation 

R  =  Smallest  permissible  radius  of  curvature  of  the  center 
line  of  canal  on  exterior  curves,  expressed  in  feet; 

F  =  The  mean  velocity  of  the  stream,  in  feet  per  second; 

A  =  The     cross-sectional    area    of    the    stream    in    square 
feet. 

The  constant,  40,  insures  a  radius  exceeding  40  feet  under  all 
circumstances,  however  small  or  sluggish  the  canal. 

A  canal  having  a  mean  velocity  of  2  feet  per  second  may 
have  a  curvature  radius  one-half  that  of  one  with  a  mean  velocity 
of  2.83,  since  the  squares  of  these  velocities  are  4  and  8 
respectively. 

Shorter  radii  may  be  used  on  interior  curves,  and  in  firmer 
material,  but  the  radius  should  be  made  longer  in  very  light 
soils  easily  eroded,  and  where  a  break  in  the  canal  would  be 
especially  disastrous,  as  on  steep  side  hills. 

The  tendency  to  erode  the  bank  on  the  outer  side  can  be 
counteracted  to  some  extent  by  a  superelevation  of  the  bottom 
of  the  canal,  or  in  other  words,  deepening  the  canal  on  the  inner 
side  of  the  curve  and  making  it  shallow  on  the  outer  side.  This 
tends  to  keep  the  thread  of  maximum  velocity  from  the  outer 
bank.  If  very  sharp  curvature  is  necessary,  the  outer  bank 
can  be  protected  by  a  blanket  of  gravel,  or  in  extreme  cases  by 
rip-rap  of  brush  or  rock.  Very  sharp  curvature  increases  the 
friction  on  the  banks,  and  may  require  a  slight  increase  of  grade 
to  compensate,  but  the  amount  of  this  is  not  accurately  known, 
and  for  moderate  or  low  velocities  is  practically  negligible. 


VELOCITY  215 

For  high  velocities  some  compensation  for  sharp  curvature 
must  be  made,  varying  with  the  roughness  of  the  channel. 

Where  the  rolling  character  of  the  country  requires  heavy 
cuts  through  ridges  to  prevent  an  excess  of  curvature,  the  same 
reason  suggests  fills  across  low  places  to  utilize  the  excavated 
material,  and  further  straighten  the  alinement.  But  while 
cutting  the  ridges  increases  the  safety  of  the  canal  and  reduces 
maintenance  charges,  the  construction  of  high  fills  has  the 
opposite  effect,  and  may  be  a  serious  matter  in  countries  where 
the  banks  are  attacked  by  burrowing  animals.  In  such  cases, 
therefore,  there  may  be  an  excess  of  excavated  material  which 
cannot  be  utilized,  both  for  the  above  reason  and  the  long  hauls 
that  its  utilization  may  involve. 

Where  the  above  circumstances  afford  a  latitude  of  choice, 
it  is  generally  advisable  to  make  two  or  more  preliminary  loca- 
tions and  compare  their  estimates  of  cost,  considering  at  the 
same  time  the  relative  safety  and  alinement  of  the  several 
locations.  Where  one  location  is  undoubtedly  safer  than 
another,  considerable  expense  may  be  justified  to  secure  such 
safety,  especially  on  large  canals,  not  only  on  account  of  the 
cost  of  maintenance,  but  also  the  security  of  the  water  supply 
where  a  break  in  a  large  canal  may  do  great  damage  directly, 
and  indirectly  involve  loss  of  crops. 

4.  Velocity. — The  velocity  given  a  canal  must  not  be  so 
great  as  to  involve  destructive  erosion  to  the  channel,  as  this 
will  increase  the  difficulty  of  diverting  the  water  into  laterals 
for  use,  endanger  the  foundations  of  bridges  and  other  struc- 
tures, and  sometimes  by  progressive  cutting  of  banks  destroy 
fertile  lands.  The  eroded  material  will  be  largely  deposited 
at  points  where  the  velocity  slackens,  and  the  regimen  of  the 
canal  will  be  thus  deteriorated. 

It  is,  however,  desirable  for  many  reasons  to  give  the  canal 
as  high  a  velocity  as  possible  without  destructive  erosion,  if  the 
necessary  grade  is  available.  Such  a  velocity  will  tend  to  prevent 
the  growth  of  aquatic  plants,  and  the  deposit  of  silt  and  trash 
in  the  canal,  and  the  necessary  water  can  be  carried  in  a  smaller 
canal  if  the  velocity  is  high  than  if  it  is  low. 


216  CANALS  AND  LATERALS 

The  maximum  permissible  velocity  depends  on  the  resistance 
to  erosion  of  the  banks  of  the  canal,  which  varies  widely  with 
different  materials.  Where  these  are  composed  largely  of  clay, 
they  may  have  a  considerable  adhesion  and  consequent  resistance 
to  erosion,  and  any  loosened  particles  in  suspension  are  easily 
transported  by  a  velocity  that  will  not  attack  the  mass  of  clay 
in  the  bank.  With  fine  sand  or  silt  the  margin  is  not  so  great, 
and  it  becomes  a  problem  of  some  difficulty  to  select  and  attain 
the  velocity  which  will  transport  all  the  silt  in  suspension  with- 
out cutting  the  banks.  When  such  a  velocity  is  found  for  the 
canal  running  at  full  capacity,  trouble  may  be  encountered  when 
the  canal  is  operated  at  part  capacity,  when  of  course  the  veloc- 
ity is  diminished,  and  the  tendencies  characteristic  of  low 
velocities  are  all  increased.  For  this  reason  it  is  important  to 
secure  the  highest  velocity  that  will  not  erode  the  banks,  and 
even  to  provide  considerable  protection  at  curves  to  prevent 
destruction  of  banks  by  erosion.  The  reduced  velocity  at  part 
capacity  causes  canals  carrying  silt-laden  water  to  deposit  silt 
when  running  part  full,  and  as  this  may  be  of  frequent  occur- 
rence such  canals  are  often  badly  silted  and  require  much  clean- 
ing. For  this  reason  a  canal  which  is  to  carry  muddy  water 
should  generally  be  constructed  with  considerable  excess 
capacity,  so  that  a  moderate  amount  of  silting  may  be  endured 
without  embarrassment,  and  the  cleaning  postponed  till  the 
winter  season.  It  is  well,  also,  to  permit  some  silt  to  remain 
permanently  in  the  canal  because  of  its  tendency  to  close  the 
crevices  and  pores  of  the  soil  and  reduce  seepage  losses  from  the 
canals  and  laterals.  A  thin  lining  of  silt  also  increases  the  dis- 
charge of  a  canal  by  forming  a  surface  smoother  than  the  original, 
and  decreasing  the  friction  of  the  water  upon  its  conduit. 

Very  few  soils,  unless  indurated  or  gravelly,  will  resist  a 
higher  mean  velocity  than  3  feet  per  second,  and  it  is  ordinarily 
necessary  to  keep  the  velocity  considerably  below  this.  Most 
soils  will  safely  stand  a  mean  velocity  of  2  feet  per  second,  and  a 
general  rule  is  that  velocities  in  earth  should  be  somewhere 
between  these  extremes,  varying  with  the  character  of  the  soil  and 
the  requirements  for  grade,  and  also  with  the  depth  of  the  canal. 


LATERAL  SYSTEMS  217 

The  erosive  power  of  a  current  depends  not  upon  the  mean 
velocity  of  the  stream,  but  upon  the  velocity  of  the  film  of  water 
around  the  perimeter  of  the  prism.  This  is  greater  in  proportion 
to  the  mean  velocity  in  shallow  than  in  deep  canals.  It  follows 
that  deep  canals  will  stand  a  higher  mean  velocity  than  shallow 
canals  in  the  same  material. 

5.  Lateral  Systems. — Every  large  canal  system  ramifies 
throughout  the  land  to  be  irrigated  somewhat  like  the  branches 
of  a  tree.  Beginning  with  the  main  canal,  this  follows  the  upper 
edge  of  the  land  to  be  irrigated,  except  in  cases  where  the  water 
is  to  be  pumped  to  still  higher  tracts.  It  may  proceed  some 
distance  before  it  reaches  any  irrigable  land.  When  it  does,  the 
land  may  be  in  a  narrow  strip  which  can  be  irrigated  from  a  single 
tap  box  or  two  in  the  side  of  the  main  canal,  but  eventually  a 
wide  tract  is  reached  which  requires  the  diversion  of  a  large 
lateral,  to  carry  a  considerable  body  of  water  to  a  large  area 
reaching  some  distance  from  the  main  canal.  Such  a  lateral 
must  also  be  located  on  high  ground  with  reference  to  the  land 
which  it  will  serve,  and  must  send  off  branches  located  also  on 
relatively  high  ground. 

On  typical  rolling  ground  where  the  normal  system  of  natural 
drainage  depressions  occur,  the  lateral  system  follows  a  rule 
generally  the  reverse  of  the  general  drainage  system.  That  is, 
the  main  canal  cutting  across  the  country  drainage  sends  out  a 
main  lateral  down  each  main  ridge,  and  this  lateral  sends  out 
smaller  laterals  down  the  subordinate  ridges,  from  which  sub- 
laterals  diverge  on  each  side.  Thus,  every  ridge  is  crowned  by  a 
lateral  and  bounded  on  each  side' by  a  ravine,  or  depression. 

The  rules  for  locating  a  lateral  system  on  such  land  are  rela- 
tively simple  as  above  indicated,  but  the  system  itself  may  be 
complicated  and  difficult  to  design,  construct,  maintain  and 
operate.  The  topography  may  require  a  large  number  of  sub- 
laterals  to  follow  each  ridge,  with  a  corresponding  number  of 
turnouts  and  tap  boxes.  Each  farm  must  have  at  least  one  tap- 
box  to  deliver  water  at  the  highest  point  of  irrigable  land,  from 
which  it  can  be  led  by  gravity  to  lower  ground.  If  the  individual 
farm  is  cut  by  a  ravine  a  second  turnout  may  be  needed,  on  the 


218 


CANALS  AND  LATERALS 


opposite  side  of  the  depression,  and  conditions  may  be  such  that 
several  of  these  may  be  required  on  a  farm  of  moderate  size. 
The  slopes  also  may  be  so  great  as  to  induce  destructive  veloci- 
ties unless  drops  are  introduced,  and  in  some  systems  hun- 
dreds of  these  are  required.  Such  a  system  will  also  have  numer- 
ous drainage  crossings  of  various  forms.  All  these  add  to  the 
complication  and  expense  in  design,  construction,  maintenance 
and  operation,  and  demand  immense  and  intense  preliminary 
study  of  the  numerous  alternatives  which  will  present  them- 
selves. These  can  be  made  most  efficiently  and  economically 


FIG.  71. — Diagram  Illustrating  Distributary  System. 

on  an  accurate  topographic  map  of  the  entire  irrigable  area  of 
suitable  scale  and  contour  interval. 

From  this  conventional  topographic  condition,  with  a  defi- 
nitely marked  system  of  natural  drainage,  we  have  all  shades  of 
variation  to  the  smooth  alluvial  valley  with  two  main  slopes, 
one  down  the  valley,  and  one  normal  to  this,  toward  the  stream. 
With  such  smooth  topography,  on  moderate  slopes,  the  distri- 
bution system  is  greatly  simplified  and  cheapened  as  compared 
with  that  on  more  rolling  country.  In  rare  cases  the  slope  may 
be  insufficient  to  furnish  the  necessary  fall  for  economical  gravity 
irrigation.  An  illustration  of  such  a  case  is  the  Minidoka 
Project  of  the  U.  S.  Reclamation  Service,  where  in  order  to  obtain 
and  keep  the  requisite  slopes  for  the  gravity  canals,  it  was  neces- 
sary to  build  a  diversion  dam  46  feet  high,  and  to  build  most  of 


LATERAL  SYSTEMS  219 

the  canals  and  laterals  between  high  banks  constructed  from 
borrow  pits,  so  that  the  water  surface  is  held  high  above  the 
adjacent  country,  thus  giving  slope  to  make  the  water  run  over 
the  surface  of  the  fields.  Such  instances,  however,  are  rare, 
as  most  irrigable  tracts  have  ample  slopes,  and  excess  slope  is 
far  more  common  than  deficiency.  The  smoothest  valley, 
appearing  to  the  eye  to  be  absolutely  level,  generally  has  slope 
enough  for  gravity  irrigation,  and  may  even  have  an  excess. 

Perhaps  the  most  difficult  type  of  land  surface  to  supply 
with  a  distribution  system  is  that  of  eolian  origin,  where  the  sur- 
face, originally  a  series  of  sand  dunes  and  depressions,  may  be 
modified  by  time  but  still  maintains  the  character,  and  is  under- 
lain with  a  subsoil  coarse  enough  to  absorb  the  meager  rainfall 
promptly,  and  no  surface  drainage  system  is  formed.  Such 
a  topography,  with  its  low  hills  and  hollows  without  law  or 
system,  presents  peculiar  difficulties  to  the  topographer,  and 
especially  to  the  engineer  designing  a  distribution  system. 
Many  of  the  shallow  depressions  are  bowls  or  sinks  without  sur- 
face outlet,  and  many  of  the  low  mounds  are  isolated  and  can 
be  reached  by  the  laterals,  if  at  all,  only  by  means  of  high  fills,  or 
by  pressure  pipes  to  carry  the  water  across  low  ground.  The 
studies  necessary  for  planning  a  system  for  such  lands  require  a 
good  topographic  map  with  less  vertical  interval  between  con- 
tours than  most  other  classes  of  topography  require,  and  such  a 
map,  though  expensive,  is  imperatively  necessary. 

The  shallow  depressions  in  this  class  of  land,  having  no  outlet, 
may  become  swamps  or  ponds  from  the  accumulations  of  surface 
drainage  or  the  rise  of  ground  water,  or  both,  and  the  lowest 
parts  of  such  bowls  should  generally  be  excluded  from  the  area 
classed  as  irrigable. 

Many  of  the  isolated  elevations  will  be  too  expensive  to  reach, 
or  the  long  fills  necessary  may  be  too  burdensome  in  mainte- 
nance, and  it  is  then  best  to  eliminate  them,  or  to  postpone  their 
development  until  land  values  have  increased  enough  to  justify 
their  reclamation.  It  should  never  be  forgotten  that  canals 
running  on  high  fills  present  especial  hazard  and  expense  in  main- 
tenance. Not  only  may  they  be  subject  to  slides,  especially  if 


220  CANALS  AND  LATERALS 

of  clayey  material,  but  they  are  the  favorite  haunts  of  burrow- 
ing animals,  and  incipient  breaks  have  such  head  of  water  that 
they  rapidly  enlarge,  and  become  disastrous. 

6.  Design  of  Laterals. — In  cross-section,  laterals  should 
usually  have  a  greater  depth  in  proportion  to  width  than  larger 
canals.  This  reduces  the  area  exposed  to  seepage  and  evapora- 
tion and  economizes  in  drops,  bridges  and  other  structures.  It 
gives  better  hydraulic  conditions  for  economizing  grade,  which 
may  be  important  in  level  country.  It  also  gives  less  encour- 
agement to  the  growth  of  weeds  on  the  margin  and  of  aquatic 
plants  on  the  bed  of  the  lateral.  In  any  canal  through  arable 
soil,  vegetation  is  sure  to  grow  along  the  margin  of  the  water, 
and  this  gradually  encroaches  on  the  waterway,  affording  a 
lodgment  for  sand  and  silt  that  may  roll  down  the  bank  or  be 
carried  there  by  the  water  or  the  wind.  Thus,  gradually  a 
turf  is  formed,  building  farther  out  into  the  canal,  protected  by 
the  roots  of  the  grass  and  weeds  growing  upon  it  and  forming 
a  new  bank  steeper  than  the  original  below  the  water  surface 
with  a  berm  just  above.  Where  ample  capacity  has  been  pro- 
vided, this  may  be  a  desirable  development,  as  it  furnishes  a 
berm  to  catch  the  material  that  may  ravel  from  the  bank,  and 
has  no  injurious  effects  on  the  waterway  if  not  carried  too  far, 
and  if  care  is  taken  to  prevent  the  development  of  noxious  weeds 
thereon.  This  tendency  to  steeper  banks  shows  the  fallacy  of 
giving  lateral  sides  especially  flat  slopes  for  the  sake  of  stability. 
Such  slopes  are  often  made  as  steep  as  45  degrees  or  steeper,  and 
it  may  be  difficult  to  maintain  them  much  flatter,  even  if  this 
were  desirable. 

For  the  sake  of  stability  previous  to  the  development  above 
described,  it  is  necessary  to  provide  side  slopes  not  steeper  than 
1 1  to  i  or  about  38  degrees  from  the  horizontal,  and  not  flatter 
than  2  to  i,  or  30  degrees  from  the  horizontal. 

The  height  of  banks  above  the  surface  of  the  water  in  the 
lateral  will  vary  with  conditions.  Where  the  lateral  is  in  fill, 
the  freeboard  must  be  greater  than  in  cut,  and  where  banks  are 
of  light,  loose  material,  liable  to  wind  erosion,  they  must  be 
higher  than  in  clay  or  gravel.  A  high  freeboard  is  not  so  impor- 


CAPACITY  OF  LATERALS  221 

tant  where  the  banks  are  thick  and  heavy  as  where  they  axe  thin. 
In  any  case  they  should  have  some  allowance  for  shrinkage  and 
wear  down,  and  still  be  high  enough  to  be  safe  against  over- 
topping with  the  most  extreme  use  to  which  the  lateral  can  be 
subjected. 

The  top  v/idth  of  banks  of  laterals,  should  vary  from  about  3 
feet  for  small  laterals,  to  5  or  6  feet  for  the  large  ones.  Above 
this,  it  is  generally  best  to  make  at  least  one  bank  wide  enough 
for  a  roadway,  at  least  10  or  12  feet,  but  this  is  advisable  only  for 
the  largest  laterals  or  main  canal. 

As  the  science  of  irrigation  develops,  and  as  the  value  of 
water  advances,  it  is  becoming  more  and  more  common  to  line 
lateral  systems,  especially  when  located  in  porous  soil  such  as 
sand  or  gravel  where  seepage  losses  would  be  heavy  without  such 
lining.  In  such  cases,  pipes  may  be  freely  used  where  the  grade 
is  abundant  without  excessive  cost,  and  with  important  saving  in 
maintenance.  Lined  canals  may  and  should  have  greater 
depth,  less  bottom  width,  and  steeper  side  slopes  than  unlined, 
as  these  differences  are  necessary  to  economize  in  the  labor  and 
material  of  the  lining,  and  also  increase  the  velocity  obtained 
which  is  generally  desirable  in  a  lined  canal,  as  tending  to  keep  it 
clear  of  sediment  and  vegetation. 

7.  Capacity  of  Laterals.  —  The  capacity  of  laterals  is  affected 
by  several  considerations,  the  main  one  being  the  acreage  to  be 
served.  Of  course  the  larger  the  tract,  the  larger  the  lateral 
necessary  to  serve  it,  but  the  ratio  is  not  constant.  A  small 
tract  is  more  likely  than  a  large  tract  to  require  irrigation  all  at 
once,  and  hence  requires  a  relatively  larger  lateral.  Laterals 
should  in  general  have  a  capacity  not  less  than  10  second-feet,  as 
such  a  quantity  may  be  necessary  for  economical  irrigation  at 
one  time  for  a  single  irrigator.  Lateral  capacity  should  never 
be  less  than  i  second-foot  to  every  60  acres  served',  nor  less  than 
10  second-feet.  Between  these  limits  a  rough  rule  is: 


where  c  =  capacity  of  lateral  in  second-feet,  and  a  =  area  to  be 
irrigated  in  acres. 


222  CANALS  AND  LATERALS 

Where  irrigation  water  carries  much  sediment  likely  to  settle 
in  laterals,  it  is  necessary  to  allow  a  large  margin  to  permit  the 
use  of  the  lateral  throughout  the  season  without  shutting  off  the 
water  for  cleaning  it.  This  margin  is  not  included  in  the  above 
rule,  but  must  be  added  to  the  value  of  c,  obtained  from  the  for- 
mula. 

In  the  case  of  the  Imperial  Valley,  California,  where  irrigation 
is  required  twelve  months  in  the  year,  and  the  irrigation  water  is 
loaded  with  silt,  an  irrigation  engineer  experienced  in  its  man- 
agement advocates  building  the  lateral  system  in  duplicate,  so 
that  one  system  can  be  used  while  the  other  is  being  cleaned,  and 
irrigation  water  can  be  delivered  without  interruption.  This, 
however,  would  require  some  provision  for  carrying  water  from 
one  lateral  across  its  duplicate,  and  the  complications  involved 
would  hardly  be  justified.  It  is  generally  possible  to  close  a 
lateral  for  a  time  in  the  slack  season,  which  varies  somewhat 
with  the  crop,  but  generally  occurs  in  winter,  so  that  cleaning 
may  be  accomplished  without  detriment  to  the  crops.  Various 
mechanical  devices  have  also  been  invented  by  which  laterals 
may  be  economically  cleaned  without  turning  out  the  water, 
and  this  subject  will  be  more  fully  treated  under  the  head  of 
"  Maintenance,"  page  518.  What  has  been  said,  however, 
clearly  shows  that  considerable  excess  capacity  of  laterals  is  a 
.great  advantage,  and  is  never  a  bad  investment  where  sediment 
is  carried  in  the  irrigation  water. 

8.  Location  of  Laterals. — Laterals  must  be  so  located  as  to 
deliver  water  to  the  highest  point  of  irrigable  land  on  each  farm 
unit,  and  their  number  and  distribution  will  hence  depend  in 
some  degree  upon  the  probable  size  of  farms.  Where  the 
topography  will  permit,  they  should  follow  property  lines  so  far 
as  possible,  for  thus  they  cause  the  least  inconvenience,  and  give 
the  greatest  service,  by  reaching  the  maximum  number  of  hold- 
ings. In  smooth  valleys  it  may  be  possible  to  run  a  lateral  down 
each  section  line,  thus  conforming  to  legal  subdivisions  of  the 
land,  and  probably  farm  units.  It  is  not  always  desirable,  how- 
ever, to  place  lateral  headings  in  the  main  canal  at  such  frequent 
intervals  as  one  mile,  as  such  structures  increase  the  costs  of 


LOCATION  OF  LATERALS  223 

construction,  maintenance  and  operation,  and  are  in  some  degree 
a  menace  to  the  continuity  of  service,  as  they  usually  constitute 
points  of  weakness  in  the  canal  banks.  In  some  cases  where 
conditions  of  topography  or  land  ownership  require  laterals  at 
frequent  intervals,  one  turnout  is  made  to  serve  two  or  more 
laterals,  by  carrying  the  water  parallel  to  the  main  canal  for  the 
distance  necessary.  The  objections  to  this  are  the  increased 
seepage  losses  from  the  parallel  canal  and  the  land  it  occupies. 
These  are  in  some  cases  unimportant,  and  in  other  cases  may 
more  than  offset  the  disadvantages  of  additional  turnouts. 

The  bottom  of  each  lateral  at  its  head  should  be  a  foot  or  two 
higher  than  the  bottom  of  the  main  canal,  so  that  sand  moving 
along  the  bottom  may  be  kept  out  of  the  lateral,  but  more  than 
this  should  be  avoided  when  possible,  as  any  greater  elevation 
may  require  the  provision  of  a  check  in  the  main  canal  to  permit 
the  diversion  of  water  into  the  lateral  when  only  part  capacity 
is  being  run,  and  checks  are  to  be  avoided  when  possible,  espe- 
cially in  silt-bearing  canals. 

Where  the  slope  of  the  country  is  very  slight,  and  the  grade 
and  velocity  of  laterals  are  necessarily  low,  it  is  generally  best 
to  make  each  lateral  serve  the  greatest  possible  area,  as  the 
larger  lateral  on  a  given  grade  will  have  a  greater  velocity, 
and  the  disadvantages  of  low  velocities  may  be  partly 
avoided. 

Laterals  are  commonly  located  on  fairly  level  ground,  and 
can  and  should  in  that  case  be  so  located  when  feasible,  that  the 
material  excavated  for  the  channel  will  be  just  sufficient  to  form 
the  banks,  and  the  channel  and  banks  together,  form  the  water- 
way of  the  required  dimensions  and  capacity.  Where  the 
ground  is  very  broken,  however,  this  rule,  if  strictly  followed, 
may  introduce  too  much  curvature,  and  to  secure  better  aline- 
ment  it  may  be  advisable  to  locate  partly  in  cut  and  partly  in 
fill,  in  which  case  it  is  often  possible  to  balance  the  cut  and  fill 
so  that  by  a  moderate  longitudinal  haulage  of  material  the 
fills  may  be  built  of  the  materials  taken  from  the  cuts  near 
enough  so  that  excessive  haulage  is  not  required.  In  making 
such  location,  it  is  always  best  to  make  the  cut  somewhat  in 


224  CANALS  AND  LATERALS 

excess  of  the  fill,  rather  than  run  any  risk  of  having  a  balance 
the  other  way. 

9.  Abnormal  Leakage  from  Canals. — In  numerous  cases 
serious  trouble  has  been  caused  and  some  canals  have  been 
rendered  useless,  by  subterranean  cavities  not  previously 
observed,  which  are  developed  by  the  introduction  of  water 
into  the  canals. 

On  the  Flathead  Project  of  the  U.  S.  Indian  Service,  a  series 
of  systems  of  small  canals  has  been  constructed,  on  which  bad 
sink  holes  and  cavities  have  appeared  without  any  previous 
surface  indications.  On  one  system  there  is  an  average  of 
twelve  such  holes  to  the  mile,  and  these  average  from  12  to  15 
feet  deep  and  200  feet  long.  On  another  small  system  there 
are  about  four  holes  to  the  mile,  which  average  6  feet  deep  and 
100  feet  long.  When  these  canals  were  constructed,  the  ground 
was  in  apparently  satisfactory  condition  for  carrying  water, 
being  of  stratified  clay.  In  a  few  places  minute  cracks  occurred 
in  cuts  about  3  feet  below  the  surface,  being  so  small,  however, 
as  to  be  hardly  nc  ticeable.  When  water  was  turned  in,  these 
cracks  enlarged,  and  in  a  short  time  the  substrata  seemed  to 
melt  away,  and  great  cavities  appeared,  absorbing  the  entire 
flow  of  the  canal,  which  disappeared  entirely.  Sometimes  by 
letting  the  water  flow  into  the  holes  for  a  time  they  would  puddle 
themselves,  fill  with  water,  and  some  repair  would  restore  the 
canal.  In  the  greater  number  of  cases,  however,  no  such  result 
followed,  and  after  developing  the  holes  thoroughly  the  water 
was  turned  out,  the  sides  of  the  holes  blasted  in,  and  the  canal 
restored  by  careful  puddling,  after  which  no  trouble  was 
experienced. 

Many  sink  holes  occurred  at  the  structures  along  the  canal, 
where  the  water  followed  down  the  cutoff  trenches,  and  thus 
reached  the  substrata.  They  are  more  numerous  in  cuts  that 
reach  the  substrata  than  at  other  places. 

The  surface  of  the  country  in  this  region  is  peculiar  in  having 
a  large  number  of  potholes  many  of  which  form  small  ponds. 
These  may  have  been  formed  by  the  collapse  of  underground 
caverns  similar  to  those  described. 


ABNORMAL  LEAKAGE  FROM  CANALS  225 

In  the  GRAND  VALLEY,  on  the  western  slope  of  the  "Rocky 
Mountains,  near.  Palisade,  Colorado,  is  a  region  where  the  soil 
having  no  abnormal  appearance  in  its  natural  state,  settles  from 
i  to  5  feet  vertically  soon  after  becoming  thoroughly  saturated 
with  water.  Settlers,  preparing  this  land  for  irrigation,  prepare 
to  "  settle  "  the  land  with  as  much  deliberation  and  matter  of 
course,  as  in  other  regions  they  clear  or  level  it.  The  "  settle- 
ment "  must  be  performed  with  care  and  skill,  or  great  trouble 


FIG.  72. — Cavity  Developed  in  Canal  Bed,  Flathead  Reservation,  Montana. 

will  result.  It  is  necessary  to  saturate  a  large  area  at  once  in 
order  that  the  settlement  may  be  as  uniform  as  possible,  and 
not  result  in  potholes  and  undulations  that  would  be  expensive 
to  level.  With  the  utmost  care,  however,  the  settlement  is  often 
uneven  and  erratic.  This  tendency,  of  course,  introduces  com- 
plications into  the  problem  of  canal  construction,  and  it  is  nec- 
sary  in  building  large  canals  to  provide  2  or  3  feet  of  extra  bank 
height,  lest  sudden  settlement  cause  disastrous  breaks.  Occa- 
sionally cracks  or  cavities  develop  in  the  canal  perimeter  through 
which  much  water  wastes,  and  which  require  careful  puddling. 


226 


CANALS  AND  LATERALS 


FIG.  73. — Cave  Developed  in  Bottom  or  Canal,  Flathead  Indian  Reservation. 


CONSTRUCTION  OF  CANALS  227 

The  main  canal  of  the  Reclamation  Project  on  Spanish 
Fork  River,  Utah,  showed  settlement  of  the  natural  ground  in 
several  places  of  from  i  to  2\  feet,  the  subsidence  appearing 
several  weeks  after  the  canal  had  been  in  use  for  the  convey- 
ance of  water. 

These  phenomena  occurred  on  steep  side  hills  on  what  was 
at  one  time  the  shores  of  Lake  Bonneville,  in  material  varying 
from  fine  silt  sand  and  gravel  to  heavy  clay  containing  some 
small  stones.  The  settlement  here  seems  to  be  due  to  the  closure 
of  cracks  and  cavities  left  by  the  caving  and  sliding  of  the  mate- 
rial on  the  hillside,  where  the  meager  precipitation  had  never 
furnished  enough  water  to  settle  it. 

The  North  Side  Twin  Falls  Irrigation  System,  Idaho,  is  built 
in  a  country  underlain  by  lava  rock  through  which  the  Snake 
River  flows  in  a  gorge  several  hundred  feet  deep.  Any  crevices 
in  the  lava,  therefore,  have  ready  communication  with  this  deep 
gorge,  and  any  water  in  them  readily  escapes.  Numerous  springs 
are  in  evidence  on  the  walls  of  the  canyon. 

Many  cases  occurred  on  the  North  Side  Twin  Falls  canals 
where  annoying  leaks  developed.  These  were  dug  clown  to  the 
rock  and  the  crevices  closed  with  concrete,  after  which  the  earth 
was  puddled  back.  The  canal  system  as  a  whole  now  shows  fair 
average  tightness. 

The  canal  system  of  the  Pecos  Irrigation  Company  near 
Carlsbad,  N.  M.,  where  it  traverses  gypsum  formations,  was 
beset  by  leaks  which  enlarged  by  erosion  and  solution  until  they 
became  so  serious  that  for  some  distance  the  canal  location  had 
to  be  abandoned  and  the  canal  rebuilt  on  a  lower  elevation. 
In  other  places  the  leakage  was  corrected  by  placing  a  lining  of 
concrete  in  the  canal. 

10.  Construction  of  Canals. — Where  large  canals  are  located 
in  heavy  cutting,  it  is  sometimes  economical  to  employ  heavy 
machinery,  such  as  the  steam  shovel,  or  the  drag-line  excavator. 
The  latter  is  especially  adapted  by  its  long  boom,  to  conditions 
where  a  wide  canal  in  earth  requires  a  long  reach.  The  steam 
shovel  is  better  adapted  to  handling  rock.  These  are  justified 
only  where  the  yardage  to  be  moved  is  large.  A  smaller  invest- 


228 

r 


CANALS  AND  LATERALS 


FIG.  74. — Building  Lateral  in  Montana  with  Ditching  Machine. 


FIG    75. — Building  Lateral  in  Montana  with  Elevating  Grader. 


CONSTRUCTION  OF  CANALS 


229 


ment  in  plant  will  secure  economical  results  by  using  the  ele- 
vating grader,  which  loosens  the  earth  and  elevates  it  into  a 
wagon  alongside,  or  on  a  canal  of  moderate  size  may  deposit  the 
earth  directly  in  the  bank.  Fig.  75.  Small  quantities  of 
work,  especially  on  small  laterals,  are  sometimes  performed 
with  the  common  slip  scraper,  drawn  by  two  horses.  But  the 
great  bulk  of  earthwork  on  canals  and  laterals  is  performed  by 
means  of  the  Fresno  scraper  (Fig.  29),  a  modification  of  the 
old-time  Buck  scraper.  The  Buck  scraper  is  especially  useful 
in  sandy  soil  with  a  low  lift  and  short  haul,  and  cheaper  work 


FIG.  76. — Building  Canal  with  Elevating  Grader. 

has  been  done  with  it  than  with  ,  any  other  implement.  A 
common  form  of  Buck  scraper  consists  of  a  working  or  frond 
board  with  an  effective  length  of  about  9  feet  and  a  height  of 
22  inches.  This  board  rests  horizontally  on  edge  on  the  ground 
and  consists  of  two  planks  each  2  inches  in  thickness,  below 
which  is  fastened  an  iron  cutting  edge  which  reaches  7  inches 
below  (Fig.  194).  At  either  end  of  the  scraper  is  a  cam-shaped 
roller  4  inches  in  height,  on  which  the  scraper  is  turned  over. 
This  board  is  fastened  at  the  back  to  a  tail  board  3  feet  9  inches 
in  length,  on  which  the  driver  stands,  and  is  drawn  forward  by 
from  two  to  four  horses,  the  scraper  being  dumped  by  the  driver 


230 


CANALS  AND  LATERALS 


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CANAL  LOSSES  AND  THEIR  PREVENTION 


233 


merely  stepping  off  the  tail  board,  the  forward  pull  upsetting  it. 
This  implement  handles  a  load  of  from  i  to  ij  cubic  yards,  while 
its  average  daily  capacity  is  about  130  cubic  yards.  For  two 
horses  a  scraper  of  this  form  is  rarely  made  over  6  feet  in  length, 
and  the  angle  of  the  face  board  to  the  ground  is  about  28  degrees, 
and  is  regulated  by  the  attachment  to  the  tail  board.  The 
Fresno  scraper  is  most  satisfactory  in  handling  tough  earth  too 
heavy  to  be  handled  by  a  Buck  scraper,  and  which  would  even 


FIG.  77. — Building  Canal  with  Fresno  Scrapers. 


give  trouble  to  a  road  scraper.  This  implement  is  usually 
drawn  by  four  horses  and  may  handle  10  cubic  yards  per  hour, 
with  an  average  load  of  ^  of  a  cubic  yard.  Its  operation  is 
illustrated  in  Fig.  77. 

ii.  Canal  Losses  and  their  Prevention. — All  earthen  surfaces, 
whether  natural  or  artificial,  absorb  more  or  less  water  when 
brought  in  contact  with  it.  This  is  the  principal  cause  of  the 
loss  of  water  carried  in  a  canal.  Though  some  water  is  also 
lost  by  evaporation  this  is  generally  less  than  10  per  cent  of  the 
quantity  lost  by  seepage.  The  quantity  lost  varies  widely 


234  CANALS  AND  LATERALS 

with  the  character  of  the  material  through  which  the  canal  runs, 
being  greatest  in  coarse  sand  and  gravel,  less  in  loam,  and  still 
less  in  clay. 

The  clay  may  have  as  great  or  greater  percentage  of  open 
space  than  the  sand,  but  the  passage  of  water  through  it  is 
slower,  owing  to  the  extreme  minuteness  of  the  openings.  In 
nearly  all  cases  the  losses  from  seepage  constitute  an  important 
factor  to  be  provided  for  and  guarded  against.  The  few  excep- 
tions are  where  a  canal  passes  through  swampy  ground,  in 
which  case  there  may  be  an  actual  gain  in  water,  the  canal 
serving  somewhat  the  function  of  a  drain. 

Where  the  canal  carries  silty  water,  there  is  a  tendency 
to  seal  the  pores  of  the  channel  and  for  this  reason  the  seepage 
from  a  new  canal  is  often  much  greater  than  it  becomes'  after 
a  long  period  of  use,  the  time  required  for  improvement  depend- 
ing upon  the  rate  of  silt  deposit. 

The  seepage  rate  increases  with  increased  temperature,  as 
the  water  partakes  to  some  extent  of  the  quality  of  viscosity 
exhibited  by  most  oils.  Where  conditions  are  favorable,  much 
of  this  seepage  water  finds  its  way  back  to  natural  drainage 
lines. 

12.  Seepage  Losses. — In  1912  and  1913,  Bark  measured  118 
sections  of  canals  in  Idaho  for  determination  of  seepage  losses. 
These  canals  varied  in  capacity  from  i  to  3200  cubic  feet  per 
second  and  the  tests  included  287  miles  of  length. 

Seven  of  the  canals  in  wet  ground  showed  a  gain.  From  the 
109  canals  showing  a  loss,  the  following  results  were  obtained: 


Per  Mile  per  cent 

Loss  per  Sq.  ft.  per  24 
Hours.      Cu.  ft. 

Maximum  loss 

58  3 

6.32 

Average  loss  

7-4 

I.  21 

This  average,  of  course,  includes  many  canals  with  losses  so 
large  as  nearly  to  destroy  their  value.  In  fact  all  the  canals 
showing  losses  greater  than  1.5  feet  in  depth  per  day  over  the 
wetted  area  should  be  classed  as  poor  in  holding  quality,  and 
improvement  by  silting,  puddling  or  lining  should  be  given 


SEEPAGE  FORMULA  235 

consideration.  For  unlined  canals  the  following  classification 
may  serve  as  a  rough  guide: 

Poor,  where  losses  exceed  1.5  feet  in  depth  per  day. 

Fair,  where  losses  are  from  i  to  1.5  feet  per  day. 

Good,  where  losses  are  from  .5  to  i  foot  per  day. 

Excellent,  where  losses  are  less  than  .5  foot  per  day. 

The  wisdom  and  character  of  improvement  will  depend  in 
each  case  not  only  upon  the  losses,  but  also  upon  the  value  of 
the  water  to  be  saved  and  the  damage  being  done  by  the  seepage, 
and  whether  other  economies  are  to  be  secured  thereby. 

13.  Seepage  Formula.—  The  following  formula  is  proposed 
as  representing  the  results  of  existing  data,  to  be  used  in  esti- 
mating seepage  to  be  expected  from  contemplated  canals: 

PL 

•>  where 


/ 
4,  ooo  +  2  ,000  VV 

S  =  Seepage  in  cubic  feet  per  second; 

C  =  Coefficient  depending  on  material  of  canal; 

d  =  Mean  depth  of  water  in  feet; 

p  =  Wetted  perimeter  in  feet; 

L  =  Length  of  canal  in  feet  ; 

F  =  Mean  velocity  of  water  in  canal. 

Values  of  C  are  as  follows: 

C  =  i  =  Concrete,  3  to  4  inches  thick; 

C  =  4  =  Clay  puddle,  6  inches  thick; 

C  =  5  =  Thick  coat  of  crude  oil,  new; 

C  =  6  =  Cement  plaster,  i  inch  thick; 

C  =  8  =  Clay  puddle,  3  inches  thick; 

C  =  10  =  Thin  oil  lining;   cement  grout; 

C  =  1  2  =  Clay  soil,  unlined  ; 

C=  15  =  Clay  loam  soil,  unlined; 

C  =  20  =  Medium  loam,  unlined. 

C—  25  =  Sandy  loam,  unlined; 

C  =  30  =  Coarse  sandy  loam,  unlined; 

C  =  40  =  Fine  sand,  unlined; 

C  =  50  =  Medium  sand,  unlined; 

C  =  70  =  Coarse  sand  and  gravel,  unlined. 


236  CANALS  AND  LATERALS 

Care  should  be  taken  not  to  give  too  much  weight  to  the 
above  arbitrary  values  of  C,  as  the  seepage  depends  not  only 
upon  the  surface  of  the  canal  perimeter,  but  also  to  some  extent 
upon  its  backing.  Any  one  of  the  linings  above  listed  will  make 
a  tighter  canal  if  placed  on  a  clay  or  loam  soil,  than  if  it  has  a 
backing  of  sand  or  gravel,  which  transmit  the  water  freely. 

14.  Canal  Lining. — It  is  becoming  more  and  more  the  prac- 
tice to  line  irrigation  canals  and  laterals,  mainly  for  the  reasons 
following : 

1.  To  prevent  loss  of  valuable  water. 

2.  To  avoid  softening  the  lower  bank  on  side  hills,  and  con- 
sequent sloughing. 

3.  To  avoid  waterlogging  land  and  thus  destroying  its  fer- 
tility. 

4.  To  prevent  erosion  of  the  canal  bed  where  high  velocities 
are  convenient  or  economical. 

5.  To  reduce  friction  and  thus  avoid  excessive  excavation  in 
heavy  rock  cuts. 

Seepage  from  canals  located  on  side  hills  often  threatens  the 
safety  of  canals  by  softening  the  lower  bank  and  causing  it  to 
slough  or  slide.  Where  water  is  valuable  the  cost  of  lining  is 
often  less  than  the  value  of  the  water  thereby  saved.  Such 
cases  are  becoming  more  frequent  as  water  increases  in  value. 
Many  cases  occur  where  seepage  from  canals  saturates  and  water- 
logs valuable  land  at  lower  levels,  and  lining  may  be  required  to 
prevent  this.  Where  the  topography  of  the  country  requires  or 
permits  a  very  heavy  grade  to  be  given  a  canal,  concrete  lining 
may  be  necessary  to  prevent  erosion,  and  by  thus  utilizing 
excess  grade  the  cost  of  drops  is  saved.  In  heavy  rock  cuts  it 
may  be  found  economical  to  provide  a  lining  to  diminish  friction 
and  thus  secure  a  sufficient  velocity  and  discharge  with  less  cross- 
section  so  as  to  save  expensive  excavation. 

The  existence  of  one  or  more  of  the  various  reasons  may  jus- 
tify the  lining  of  a  canal  and  lateral  system  throughout.  This 
has  been  done  by  the  U.  S.  Reclamation  Service  where  the  land 
is  very  sandy,  upon  the  west  extension  of  the  Umatilla  Project 
covering  about  10,000  acres.  It  is  also  frequently  done  in 


CANAL  LINING  237 

Southern  California  where  water  is  very  valuable.  It  is  thus 
possible  to  eliminate  many  drops  that  would  otherwise  be  re- 
quired upon  the  lateral  system,  and  to  employ  velocities  higher 
than  earth  sections  would  permit,  and  thus  keep  the  canals  free 
from  silt,  trash  and  vegetation. 

Canal  lining  is  usually  of  cement  mortar  or  concrete,  but  in 
some  cases  other  materials  have  been  used.  Where  a  canal  is 
constructed  on  a  long  fill  which  might  settle  unevenly  and  thus 
crack  a  concrete  lining,  and  where  seepage  would  endanger  its 
safety  if  unlined,  lumber  is  sometimes  used  for  lining,  with  the 
expectation  of  replacing  this  when  decayed,  with  concrete  lining, 


FIG.  78. — Cross-section  of  Lined  Channel,  Santa  Ana  Canal. 

after  the  bank  is  well  settled.  Wooden  lining  may  be  used  where 
the  ground-water  is  impregnated  with  salts  to  such  extent  as  to 
disintegrate  concrete  lining. 

Concrete  linings  are  usually  made  from  2  inches  to  4  inches 
in  thickness,  and  joints  running  across  the  canal  are  necessary 
at  intervals  of  from  20  to  40  feet,  to  prevent  irregular  contraction 
cracks.  It  is  best  to  place  the  concrete  in  cold  or  cool  weather,  to 
avoid  subsequent  cracking,  and  to  build  alternate  slabs  which 
are  allowed  to  harden  before  the  intermediate  slabs  are  placed. 
In  cold  climates,  where  hard  freezing  is  common,  •  it  may  be 
advisable  to  reinforce  the  slab  with  steel  fabric  or  mesh  to  hold 
it  together  against  heaving.  If  there  is  possibility  of  collection 
of  water  behind  the  slabs,  this  may  be  relieved  by  the  provision 
of  one  or  more  weep  holes  near  the  center  of  the  bottom  slabs, 
and  in  the  side  slabs  near  the  bottom.  The  joints  may  be  relied 
upon  to  allow  the  escape  of  water  in  their  vicinity. 


238  CANALS  AXD  LATERALS 

If  the  side  slopes  are  made  45  degrees  or  flatter,  they  may 
readily  be  placed  without  forms,  by  taking  care  to  have  the 
consistency  of  the  concrete  suitable  to  such  use.  If  the  depth 
of  cut  requires  for  economy  a  steeper  slope  than  45  degrees, 
it  will  be  necessary  to  provide  forms  for  the  lining,  which  will 
increase  its  cost.  The  outside  bank  can  sometimes  be  made 
flatter,  and  the  form  avoided. 

In  countries  where  the  winters  are  mild,  a  very  thin  lining 
has  sometimes  been  used  made  of  cement  mortar  or  of  concrete 
with  small  aggregates,  plastered  directly  on  the  earth  bottom 
and  slopes,  from  f  to  i|  inches  thick,  without  forms,  and  without 
reinforcement.  If  this  is  carefully  placed  in  cool  weather,  and 
protected  from  drying  until  thoroughly  set,  good  results  may  be 
obtained  very  cheaply.  Such  linings  have  been  extensively 
and  successfully  used  on  the  Umatilla  Project  of  the  U.  S. 
Reclamation  Service.  They  would  not  succeed,  however, 
where  the  ground  is  subject  to  heaving. 

Ir  cases  where  ground-water  is  strongly  impregnated  with 
alkaline  sulphates  which  threaten  to  disintegrate  the  concrete 
lining,  the  difficulty  may  be  met  by  providing  free  drainage 
for  the  ground-water,  and  by  placing  2  or  3  inches  of  screened 
gravel  under  the  concrete  slabs  to  facilitate  the  escape  of  ground- 
water  through  tiling  placed  for  the  purpose. 

In  some  cases  where  canals  are  located  on  steep  side  hills, 
they  may  be  threatened  by  slides  of  snow  or  earth  from  the  steep 
hillside  above,  and  a  protective  covering  may  be  necessary  to 
prevent  disastrous  breaks  from  this  cause.  A  reinforced  con- 
crete arch  has  been  successfully  used  for  this  purpose  in  the 
Spanish  Fork  Valley  by  the  U.  S.  Reclamation  Service. 

Concrete  lining  should  be  placed  only  on  well-settled  banks; 
otherwise  unequal  settlement  will  be  likely  to  rupture  the  lining, 
thus  reducing  its  efficiency,  and  hastening  disintegration. 

The  earth  upon  which  the  lining  is  built  should  be  carefully 
smoothed  and  rolled,  and  if  dry  it  is  best  to  moisten  it  before 
placing  the  concrete,  as  dry  earth  will  absorb  some  of  the  moisture 
which  the  concrete  requires  for  the  chemical  process  of  setting. 
The  concrete  mixture  should  be  about  one  part  of  cement  to 


CANAL   LINING 


239 


FIG.  79. — Check  Gates  and  Canal  Lined  on  One  Side.     Interstate  Canal, 
Nebraska-Wyoming. 


FIG.  80. — Semicircular  Concrete-lined  Section  of  Main  Canal,  Umatilla  Valley, 

Oregon. 


240 


CANALS  AND  LATERALS 


two  of  sand  and  four  of  gravel.  The  diameter  of  the  largest 
particles  of  the  gravel  should  not  exceed  one-half  the  thickness 
of  the  lining  and  where  the  lining  is  less  than  ij  inches  thick, 
it  is  usually  best  to  omit  the  gravel,  and  use  a  mortar  of  i  part 
cement  to  three  parts  of  well-graded  sand. 


FIG.  81. — Concrete  Lining.  Truckee-Carson  Canal,  Nevada. 

A  typical  paved  lining  is  that  given  the  Santa  Ana  canal  in 
California,  in  alluvial  soil,  sand,  and  gravel.  This  canal  is 
almost  wholly  in  excavation  (Fig.  78) ;  the  water  is  permitted  a 
velocity  of  5  feet  per  second,  and  the  depth  is  as  great  as  7^ 


CANAL  LINING 


241 


feet  for  a  bed  width  of  6J  feet  and  top  width  of  12^  feet.  In 
order  that  the  lining  may  have  a  stable  footing  and  the  bottom 
be  less  liable  to  bulge,  this  is  curved  downward  with  a  versed  sine 
of  i \  feet,  forming  thus  a  subgrade  of  that  depth.  The  banks 
are  2  feet  higher  than  the  water  surface,  and  are  built  on  side 
slopes  of  2  on  i.  The  earth  excavation  had  a  bottom  width  of  7 
feet  and  the  same  slopes  as  above,  and  was  trimmed  at  bottom  to 
the  lining,  which  consists  of  cobbles  and  bowlders  laid  in  mortar, 
grouted  and  faced  with  cement  plaster. 

On  the  Tie  ton  canal,  Washington,  of  the  Reclamation  Service, 
the  lined  sections  in  earth  and  loose  rock  are  semicircular  (Fig. 


r  ~& 

\:  ; 

\_|^Mortar 

Joint 

DETAIL  OF  JOINT 

l"  Square^ 

^  -T)--^  PA 

Back  fill 

rrig'2-:-    --^ 
FIG.  82. — Reinforced  Concrete  Canal  Lining.     Tieton  Canal,  Washington. 

82).  The  lining  is  of  reinforced  concrete,  4  inches  in  thickness, 
and  extends  i  foot  10  inches  above  the  center  of  the  circular 
section.  The  upper  edge  is  cross-braced  every  2  feet  by  a  4-inch 
square  brace.  The  diameter  of  the  lined  section  is  8  feet 
2  inches,  depth  of  water  5  feet  3  inches,  area  36  -square  feet, 
velocity  9  feet  per  second,  and  discharge  326  second-feet.  By 
comparison  the  unlined  section  of  the  same  canal  has  an  area  of 
120  square  feet  and  velocity  of  2.5  feet  per  second. 

Below  the  Assuan  dam  in  upper  Egypt  is  a  canal  built  in 
shifting  sand  by  erecting  on  the  surface  a  semicylindrical  flume 
of  sheet  steel  and  then  banking  the  sand  against  it  to  the  level  of 


242 


CANALS  AND  LATERALS 


SECTION  "A-A" 


its  top.  This  steel  canal  is  19  feet  8  inches  in  diameter  with 
i  foot  8  inches  straight  sides  at  top,  making  a  total  depth  of 
21  feet  4  inches.  The  inner  shell  of  J-inch  steel  plates  is  riveted 
to  outer  semicircular  ribs  of  heavy  T-rail  placed  2^-feet  centers. 
The  top  is  braced  with  3-inch  flat  and  3  inch  by  2\  inch  angle 
iron.  The  canal  rests  on  a  wall  of  concrete  beneath  its  center 

and  has  expansion  joints  every  330 
feet. 

Experiments  conducted  by  B. 
A.  Etcheverry  in  Southern  Cali- 
fornia to  determine  relative  per- 
colation from  lined  and  unlined 
ditches  showed  the  following  rela- 
tive efficiency  ratios.  Using  un- 
lined earth  channels  e—  i.o;  heavy 
oil  lining,  3!  gallons  per  square 
yard,  e  =  2.o'y  clay  puddle,  e  =  i.8; 
cement  concrete  3  inches  thick, 
6  =  7.2. 

Careful    cost    records    kept  on 
the      Orland     Irrigation     System 
embracing    both    unlined    canals, 
and    others    lined    with    concrete, 
show  a  maintenance   cost  for  the 
unlined    canals   of   $123   per   mile 
per  annum,  and  $10  for   the  lined 
FIG.  83.— Transition  from  Rock  to    canals.     The   lining    has    also    re- 
Earth  Cross-section,  Lined  Canal,     duced  the  seepage  losses,  Until  this 
Reclamation  Sendee.  ,          f  ,       ,.       , 

loss  from  the  lined  canals  is  about 

one-tenth  as  great  relatively  as  from  those  that  have  not  been 
lined. 

On  the  main  canal  of  the  Carlsbad,  New  Mexico  project, 
37,300  linear  feet  of  canal  were  lined  with  concrete  two- tenths  of 
a  foot  in  thickness.  This  required  7,191  cubic  yards  of  concrete 
at  $13.67— $98,313,  or  $2.64  per  linear  foot,  or,  $13,820  per 
mile. 

The  lining  of  the  laterals  on  the  same  project,  was  accom- 


Rip  Rap 
6  "thick 


CANAL  LINING 


243 


plished  at  a  cost  of  $10.37  Per  cubic  yard  of  concrete  of  a  thick- 
ness of  .2  of  a  foot. 

The  lining  of  the  main  canal  on  the  Umatilla  project,  Oregon, 
with  concrete,  3  inches  thick,  in  the  proportion  of  i  :  3.5  :  5.2, 
cost  $8. 1 6  per  cubic  yard,  and  carried  a  little  more  than  a  barrel 
of  cement  to  the  cubic  yard.  The  side  slopes  were  ij  to  i,  and 
were  lined  without  forms. 

The  main  canal  of  the  Boise  project  was  lined  with  concrete 
4  inches  thick,  with  joints  at  16  foot  intervals.  The  records 
show  the  following  costs: 


Cost  per  Cu.  yd. 
of  Concrete 

Cost  per  Linear 
Foot  of  Canal 

Plant  charge.    . 

$0   858 

$0   80  1 

Gravel  and  sand  
Cement 

1.079 
2    06^ 

1.008 
2     76? 

Water  

O    222 

o  207 

Forms 

o   177 

o  165 

Mixing  and  placing  

I    603 

I    CQ7 

Supplies. 

O    IO7 

O    TOO 

Superintendence  and  accounts  

0172 

o  161 

Engineering. 

o  008 

o  092 

Total  for  concrete  . 

$7  279 

$6  708 

Preparation  of  foundation  

2  .  349 

2  .  I(K 

Grand  Total 

$9  628 

$8    QQ3 

The  U.  S.  Reclamation  Service  has  in  several  instances 
employed  clay  puddle  with  satisfactory  results,  to  tighten  the 
open  soil  of  the  canal  perimeter.  Puddle  lining,  4  inches  thick, 
has  cost  on  an  average  about  i  cent  per  square  foot,  exceeding 
this  where  the  haul  for  the  clay  was  long,  and  being  less  where 
all  the  conditions  were  favorable. 

On  the  Grand  River  project  in  Colorado,  some  of  the  canal 
location  was  in  shale  with  many  open-  seams  which  wasted  much 
water  to  the  injury  of  lands  below  upon  which  the  water  emerged, 
forming  bogs  or  swamps.  After  some  exposure  to  the  air,  the 
shale  disintegrated  to  some  extent  on  the  surface,  and  then  was 


244 


CANALS  AND  LATERALS 


plowed,  and  after  some  weathering  was  harrowed,  the  water 
turned  in,  and  harrowed  again,  forming  a  clay  puddle  which 
was  very  effective  in  reducing  the  seepage.  In  addition  to  this 
muddy  water  was  turned  into  the  canal  and  ponded  at  points 
where  seepage  was  great,  and  by  depositing  its  mud  greatly 
reduced  the  seepage.  Similar  measures  have  been  employed 
in  many  other  places  with  good  results. 


FIG.  84. — Lining  Canal  with  Concrete,  Idaho. 


On  the  Minidoka  project  clear  water  was  carried  in  a  canal 
built  partly  through  coarse  sand  in  which  losses  were  very  great, 
and  it  was  after  several  years  decided  to  try  to  reduce  the 
losses  by  depositing  silt  in  the  canal.  To  accomplish  this,  a 
deposit  of  clay  was  selected  near  the  canal,  and  water  was 
pumped  from  the  canal  through  a  hydraulic  monitor  and  the 
clay  was  by  this  means  washed  into  a  flume  and  carried  into 
the  canal  and  deposited  by  ponding  or  checking  the  canal 
where  the  puddle  was  needed.  The  result  of  this  work  was  the 


AMOUNT  OF  RETURN  SEEPAGE  245 

deposit  of  about  100,000  cubic  yards  of  clay  over  the  perimeter 
of  the  canal  at  a  cost  of  about  20  cents  per  cubic  yard.  Where 
this  was  done  the  losses  from  the  main  canal  were  reduced  from 
no  cubic  feet  per  second  in  1912,  to  71  cubic  feet  per  second  in 
1915,  besides  important  reduction  of  losses  in  the  laterals. 

15.  Amount  of  Return  Seepage. — The  State  Engineer  of 
Colorado  conducted  measurements  of  seepage  water  returned 
to  the  South  Platte  and  Cache  la  Poudre  rivers  during  the 
years  1890  to  1893  inclusive.  These  showed  a  constant  increase 
in  the  amount  of  seepage  water  returned  to  these  streams  and 
available  for  diversion  below  the  points  of  measurement. 

Prof.  L.  G.  Carpenter  sums  up  his  investigations  on  this 
subject  thus:  "  There  is  real  increase  in  the  volumes  of  streams 
as  they  pass  through  irrigated  sections.  This  increase  is 
approximately  proportional  to  the  irrigated  area.  The  passage 
of  seepage  water  through  it  is  very  slow.  The  amount  of 
seepage  water  slowly  but  constantly  increases.  This  seepage 
water  adds  to  the  amount  of  culturable  land.  On  the  Cache 
la  Poudre  River  about  30  per  cent  of  the  water  applied  in 
irrigation  is  returned  to  the  river." 

Investigations  of  a  similar  nature  conducted  by  the  Utah 
Agricultural  Experiment  Station  and  by  others  point  in  the 
same  direction.  The  amounts  of  returned  water  by  seepage 
indicated  in  the  above  experiments  must  not  be  taken  as  a  cri- 
terion of  what  may  be  expected  in  other  regions.  The  cir- 
cumstances surrounding  these  cases  were  especially  favorable 
for  the  return  of  seepage  water.  In  other  regions  the  amount 
of  seepage  water  returned  may  diminish  to  practically  nothing, 
dependent  upon  the  soil,  quality  of  underlying  strata,  their  slope 
and  inclination,  and  the  area  of  drainage  basin  above  and  trib- 
utary to  them. 

Observations  made  at  storage  reservoirs  for  New  York  and 
Boston  and  some  other  Eastern  cities  show  clearly  that  the 
amount  of  seepage  water  returned  from  the  surrounding  country 
to  reservoirs  which  have  been  drawn  down  for  service  varies 
between  10  and  30  per  cent  of  their  capacities.  This  is  largely 
due  to  the  fact  that  the  water  plane  of  the  surrounding  country 


246  CANALS  AND  LATERALS 

is  filled  up  from  the  reservoir  as  well  as  from  seepage  from  the 
adjacent  country.  Measurements  of  volume  in  the  Sweetwater 
reservoir  in  Southern  California  show  that  after  water  ceases 
to  be  drawn  from  the  reservoir  it  begins  to  refill  while  no  water 
is  entering  from  streams,  and  similar  additions  from  seepage 
have  occurred  in  other  reservoirs.  As  a  result,  the  actual 
available  capacity  of  a  storage  reservoir  may  be  found  to  be 
greater  than  its  measured  capacity. 

REFERENCES  FOR  CHAPTER  XIII 

FORTIER,  SAMUEL.     Concrete  Lining  as  Applied  to  Irrigation  Canals.     Bulletin 

No.  126,  U.  S.  Office  of  Experiment  Stations. 
MEAD  AND  ETCHEVERRY.     Lining  of  Ditches  and  Reservoirs  to  Prevent  Seepage 

Losses.     Bulletin    No.     188,    Agricultural    Experiment    Station,    Berkeley, 

California. 
ETCHEVERRY,    B.    A.     Conveyance    of   Water.     McGraw-Hill    Book   Company, 

New  York. 
CARPENTER,  L.   G.     Losses  from  Canals  from  Filtration  or  Seepage.     Bulletin 

No.  48,  State  Agricultural  College,  Fort  Collins,  Ccl. 
MORITZ,  E.  A.     Seepage  Losses  from  Earth  Canals.     Engineering  Neu's,   Aug. 

28,  1913. 
HANNA,  F.  W.     Water  Losses  in  Irrigation  Canals,  and  Methods  of  Prevention. 

Engineering  and  Contracting,  Oct.  9,  1912. 

FORTIER,  SAMUEL.     Conveyance  of  Water.     Water  Supply  Paper  43,  U.  S.  Geo- 
logical Survey, 


CHAPTER  XIV 
CANAL   STRUCTURES 

i.  Classification. — The  term  "  Canal  Structure  "  is  usually 
applied  to  all  structures  necessary  in  connection  with  the  canal, 
aside  from  the  earthen  waterway  itself,  and  its  lining,  which 
may  be  classified  as  follows: 

1.  Works  for  controlling  canal  water. 

a.  Headworks. 

b.  Turnouts. 

c.  Spillways. 

d.  Drops,  and  checks. 

e.  Measuring  devices. 

2.  Drainage  crossings. 

a.  Flumes,  and  superpassages. 

b.  Inverted  siphons. 

c.  Culverts. 

d.  Pipes. 

3.  Highway  crossings. 

2.  Location  of  Headworks. — The  first  requirement  for  a 
suitable  diversion  point  is  permanence  of  the  stream  channel, 
so  that  the  stream  will  not  leave  the  works  after  they  are 
built,  nor  wash  them  out.  Preferably  both  sides  of  the  stream 
should  be  rock  or  hard  gravel  not  easily  eroded.  It  is  especially 
desirable  that  the  side  on  which  the  regulator  is  built  should  be 
of  this  character,  for  the  safety  of  the  works,  which  should,  if 
possible,  be  founded  upon  rock. 

It  is  desirable  that  the  ground  in  which  the  first  few  rods  of 
the  canal  is  built  should  be  of  firm  material,  and  so  high  as  to  be 
not  subject  to  overflow  from  the  stream,  so  that  the  canal  will 
thus  be  protected  until  it  gets  away  from  the  river. 

247 


248 


CANAL  STRUCTURES 


The  diversion  works  should  be  located  so  far  as  physical 
conditions  will  permit,  at  such  an  elevation  as  to  command 
the  land  to  be  irrigated,  with  ample  grade  allowance  for  the 
canal,  without  an  excess  of  grade.  The  location  should  permit 
of  the  construction  of  regulating  works  parallel  to  the  stream 
so  that  the  current  of  the  stream  may  have  a  clear  sweep  past 
the  regulator,  and  close  to  it,  to  facilitate  sluicing  away  sand 
and  gravel  that  threaten  to  pass  into  the  canal. 

It  is  always  desirable  to  secure  rock  foundation  for  the 
diversion  weir,  but  if  this  is  impracticable,  a  safe  dam  can  be 


EUCC7.0 


sq.  bars  6"c.to  c. 

\"\ El.  1612.0 

?.5WP.9'.9.\ft.<5?.-.«a.V.'.4  ?????.•?.«?•«• 


'$O&  ^>°G  ••'£'•* Q«&& 

^O.S4nd;<  jrfavel^n^  UulQ 


Cut  off  wall  to  extend  SECTION  A-A 

3  into  shal. 

FIG.  85. — Cross-section  of  Corbett  Weir,  Shoshone  Project,  Wyoming. 

built  by  taking  proper  precautions,  upon  gravel,  sand,  silt  or 
clay. 

3.  Canal  Headgates. — Every  canal  should  have  one  or  more 
headgates  so  located  that  the  quantity  of  water  admitted  to 
the  canal  shall  be  at  all  times  under  control. 

On  streams  carrying  sediment  or  transporting  sand  or  gravel, 
means  should  be  provided  for  preventing  the  entrance  to  the 
canal  of  sand  and  gravel  likely  to  deposit  and  clog  the  canal. 
The  lighter  silt  which  is  easily  carried  in  suspension  is  not  so 
objectionable,  as  it  can  be  mostly  carried  through  the  canals 
and  laterals  and  deposited  on  the  fields,  where  it  has  considerable 


CANAL  IIEADGATES 


249 


fertilizing  value.  The  heavier  silt,  sand  and  gravel  are  more 
likely  to  be  deposited  in  the  canals  and  entail  great  expense  for 
removal,  and  even  if  carried  to  the  fields  are  nuisances  which 
should  be  eliminated  at  every  opportunity,  and  if  possible 
they  should  be  left  in  the  river  bed.  To  accomplish  this  three 
precautions  may  be  employed: 


10  20  30 


FIG<  86.— Plan  of  Corbett  Dam  and  Head  works,  Shoshone  Project,  Wyoming. 

1.  The  stream  velocity  may  be  reduced  before  entering  the 
canal,  thus  causing  the  settlement  of  the  heaviest  particles  in 
suspension. 

2.  The  water  entering  the  canal  may  be  required  to  flow 
in  a  thin  sheet  over  the  top  of  a  long  weir  so  that  only  the  sur- 
face water  can  enter  the  canal,  as  the  surface  carries  only  the 
lightest  sediment. 


250 


CANAL  STRUCTURES 


3.  Means  should  be  provided  for  sluicing  the  deposited 
sand  away  from  the  headworks,  and  causing  it  to  pass  on  down 
stream. 

To  secure  these  conditions,  a  diversion  dam  is  necessary, 
to  form  a  settling  basin,  and  to  furnish  head  for  sluicing  it  out 
when  needed.  The  gates  through  which  the  water  enters  the 
canal  should  be  parallel  to  the  stream,  so  that  the  water  passing 
into  the  canal  shall  move  normal  to  the  river  channel.  Immedi- 


•4  I  NOTE: 

7  a   5  gates  each  1  feet  high 

W       "'"" 


"'<*-  —  •            -"5'5— ,—•.-" '     •""*!      SECTIONAL 
"„  i  ••* 4  11 ---*  |      ELEVATION 


CROSS  SECT'ON 

DETAILS  OF  GATE 


FIG.  87.' — Wooden  Gate,  Leasburg  Canal  Regulator,  Rio  Grande,  N.  M. 
FIG.  88. — Iron  Regulator  Gate,  Minidoka  Canal,  Idaho. 


ately  adjacent  to  the  entrance  of  the  canal,  and  at  right  angles 
thereto,  at  the  end  of  the  diversion  dam,  one  or  more  sluice 
gates  should  be  placed,  with  their  sills  at  the  normal  bed  of  the 
river,  which  can  be  quickly  opened  and  as  readily  closed.  When 
opened  the  water  will  rush  through  under  the  :head  equivalent 
to  the  difference  of  water  level  above  and  below  the  dam,  and 
the  high  velocity  thus  generated  will  scour  the  channel  immedi- 
ately in  front  of  the  entrance  to  the  canal,  and  thus  furnish 


CANAL  HRADGATES 


251 


capacity  for  subsequent  use  as  settling  basin,  to  be  again  sluiced 
out  when  filled. 

The  entrance  to  the  canal  should  be  controlled  by  flash 
boards  or  some  similar  device  so  arranged  that  the  water  will 
flow  into  the  canal  as  a  thin  film  from  the  surface  only,  and 
thus  carry  on  a  skimming  process,  the  heavier  sediment  being 


TOP  VIEW 


Cast 


[ron  Shutter 


— & 


•^       cl 
FRONT  VIEW 


SEC.    C-d 


i  •        .  .               j 

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5 

2  z  %  Bronze   J^                                                                . 

^^v^v^xvvvw^^^^ 

-r 

SEC.  a-b 
FIG.  89. — Cast-iron  Sluice-gate,  Interstate  Canal,  Nebraska-Wyoming. 


generally    some    distance    below    the    surface,    especially    after 
the  velocity  of  the  water  has  been  checked. 

One  of  the  best  examples  of  the  system  here  described  is 
in  use  at  the  Laguna  Dam  on  the  Colorado  River,  at  the  head 
of  the  Yuma  main  canal  (Fig.  94.)  In  this  case  the  canal 
entrance  or  "  regulator  "  is  controlled  by  flash  boards  On  the 
Carson  River  the  regulator  is  a  movable  gate  which  is  depressed 
into  a  chamber  below  the  canal  bed  to  open  the  gate,  and  is 


252 


CANAL  STRUCTURES 


CANAL  HEADGATES 


253 


254 


CANAL  STRUCTURES 


CANAL  HEADGATES 


255 


256 


CANAL  STRUCTURES 


I 
I 


CANAL  HEADGATES 


257 


lifted  to  close  it,  the  water  entering  over  the  top  of  the  gate 
like  a  weir,  which  thus  exercises  the  skimming  function.  A 
similar  effect  is  obtained  by  inclined  gates  at  the  head  of  the 
Goulburn  Canal,  Australia  (Fig.  92).  Flash  boards,  though 
cheap,  are  slow  and  laborious  in  manipulation,  and  except  on 
very  silty  streams,  the  practice  is  usually  to  use  ordinary  iron 
gates  as  regulators. 

Where  the  conditions  of  water  supply  are  such  as  to  require 
the  diversion  of  all  the  water  in  the  stream  most  of  the  time, 


FIG.  95. — Whalen  Diversion  Dam  and  Headgates,  Normal  to  Dam.    North  Platte 

River,  Wyoming. 

there  is  little  virtue  in  the  skimming  process.  Headgates  are 
usually,  therefore,  of  the  ordinary  type,  which  .open  at  the 
bottom  by  raising  on  a  stem,  and  are  sometimes  called  under- 
shot gates,  because  the  water  passes  under  them. 

Sluicing  devices  are  most  needed  upon  streams  carrying 
much  sediment  like  those  of  the  Southwest,  but  are  also  very 
useful  upon  many  Northern  streams  which  may  generally  run 
clear,  but  nevertheless  carry  much  sand  and  gravel  by  rolling 


258 


CANAL  STRUCTURES 


along  the  bottom,  and  if  this  is  allowed  to  enter  the  canal, 
it  causes  much  annoyance  and  expense.  Instances  are  not 
rare  where  the  gravel  carried  into  the  canal  during  the  June 
rise  so  depleted  its  capacity  that  it  could  not  carry  the  water 
needed  for  irrigation,  and  it  became  necessary  to  close  the  canal 
and  clean  it  during  the  height  of  the  irrigation  season,  at  great 
expense,  and  to  the  great  injury  of  crops. 


BB 


FIG.  96. — Sprague  River  Dam,  Klamath  Indian  Reservation,  Oregon. 


The  headworks  of  a  large  canal  are  of  great  importance  for 
protecting  the  canal  against  floods,  and  for  regulating  the  flow 
into  the  canal.  They  should  be  founded  upon  rock  if  possible, 
and  should  be  of  masonry  of  gravity  design,  heavy  enough  to 
resist  any  tendency  to  shear,  slide  or  overturn  when  subjected 
to  the  maximum  pressure  which  can  occur.  They  should  be 
flanked  with  ample  wing  walls  and  unless  founded  on  rock 
should  have  deep  cut-off  walls  to  prevent  seepage  around  or 
under  them. 


CANAL  HEADGATES 


259 


260 


CANAL  STRUCTURES 


Fro.  98. — Jackson  Lake  Dam,  Downstream  Face,  Wyoming. 


FIG.  99. — Headgates  and  Sluice  Gates,  Montrose  and  Delta  Canal,  Uncompahgre 

Valley,  Colorado. 


CANAL  IIEADGATES 


261 


FIG.  loo.— Division  Gates  and  Drops  on  Tsar  Canal  near  Byram  All,  Murgab 

Valley,  Turkestan. 


FIG.  ioi.— Headworks  of  Sultan  Yab  Canal  at  Sultan  Bend  Reservoir,  on  Murgab 

River,  Turkestan. 


262 


CANAL  STRUCTURES 


TURNOUTS 


263 


4.  Turnouts. — Each  lateral  branch  from  the  main  canal  and 
all  the  sublaterals  down  to  the  individual  farm  laterals,  should 
be  provided  with  regulators.  They  are  similar  in  function  to 
the  regulator  at  the  head  of  the  main  canal,  but  differ  widely 


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ELEVATION 

FIG.  103. — Wooden  Head  to  Lateral,  Sun  River  Canal,  Montana. 

from  it,  not  only  in  size,  but  in  not  being  required  to  withstand 
the  torrents  of  the  river,  and  instead  of  keeping  out  sediment, 
should  facilitate  its  passage  through  the  system  and  its  deposit 
upon  the  land.  They  are  consequently  best  of  the  undershot 
type,  so  as  to  stop  as  little  of  the  sediment  as  may  be.  Turn- 


264  CANAL  STRUCTURES 

outs  are  usually  located  in  an  artificial  bank  of  a  canal,  and  must 
be  carefully  designed  and  built  with  a  view  to  preventing  the 
percolation  of  water  around  them.  They  must  be  provided  with 
wingwalls  with  earth  carefully  puddled  against  them.  The 
tendency  of  percolating  water  is  to  follow  in  straight  or  nearly 
straight  lines  the  seam  formed  by  the  contact  of  the  structure 
with  the  bank,  and  this  tendency  can  best  be  met  by  providing 
numerous  abrupt  angles  to  interrupt  the  path  around  the  struc- 


FIG.   104.  -Check  and  Parm  Turnout  with  Inclined  Valve. 

ture.  If  the  structure  is  of  concrete,  angular  corrugations  may 
be'  produced  by  nailing  2-  by  4-inch  lumber  vertically  to  the 
forms  against  which  the  concrete  is  afterward  built,  and  into 
these  corrugations  the  earth  fill  should  be  carefully  puddled 
and  tamped. 

The  smaller  turnouts  are  often  in  the  form  of  a  box  or  pipe 
leading  through  the  bank,  with  a  gate  on  the  upper  end.  Earthen 
sewer  pipe  is  best  for  this  purpose,  and  standard  steel  gates 


TURNOUTS 


265 


and  gate  frames  are  on  the  market  which  are  conveniently 
fastened  to  such  pipes. 

Turnouts  should  be  located  at  or  near  the  bottom  of  the  canal 

% 

from  which  they  take  water,  in  order  that  a  supply  of  water 
may  be  drawn  when  the  canal  is  running  at  part  capacity. 
Where  the  elevation  of  the  land  is  too  high  to  permit  this,  it 
may  be  necessary  to  locate  the  turnout  several  feet  above  the 
bottom  of  the  canal,  and  such  cases  will  require  the  provision  of 


FIG.  105. — Cast-iron  Valve  on  Small  Lateral  Turnout. 

a  check  in  the  canal  below,  in  order  to  hold  the  water  up  and 
enable  a  supply  to  be  taken  when  the  canal  is  only  partly  filled. 
Such  checks  are,  however,  to  be  avoided  if  possible. 

In  early  canal  building  most  of  the  structures  were  made  of 
wood,  and  this  is  still  common  practice  with  the  small  lateral 
turnouts,  which  can  be  replaced  with  little  interference  with  the 
water  service.  All  large  turnouts  which  serve  important  areas, 
and  require  considerable  time  for  renewal,  should  be  built  of 


2(>G 


CA NA L  STRUCTURES 


TURNOUTS 


267 


268 


CAXAL   STRUCTURES 


concrete  or  other  permanent  construction.  The  capacity  of 
the  conduit  should  be  sufficient  to  take  the  required  amount  of 
water  at  the  lowest  stage  of  the  canal. 


Bars  from  both  side  and 
»-mg  walls 

round  corners. Alternate 
bars  from  both  sets  in 
f  fillet. 


FIG.    108. — Reinforced    Concrete   Turnout   with    lo-Foot   Drop,   Garland   Canal, 

Wyoming. 

The  velocity  of  flow  may  be  obtained  from  the  formula 
V  =  C\/2gh,  where  h  is  the  available  head  in  feet,  g  represents 
the  acceleration  of  gravity,  in  feet  per  second,  and  C  represents  a 


TURNOUTS 


269 


constant  depending  partly   upon   the  shape,   and   partly  upon 
the  size  of  the  orifice,  and  is  greater  for  a  bell-shaped  approach 


i 


• 

\ 

< 

Cast 

\ 

Iron                       /^ 
1    /           / 

* 
I     • 

1  +  

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Vc 

1 

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5 

^ 

o 

1  •  •• 

1  1. 

'III 

ELEVATION 


SECTION   Cl-b 


iiolior 
Bolt 


.1 


SECTION    C-d 


FIG.  109. — Cast-iron  Gates  for  Laterals,  Interstate  Canal,  Nebraska-Wyoming. 


than  an  angular  opening.     It  is  usually  somewhat  less  than  .8, 
so  that  the  formula  may  be  written  roughly  V  =  6V//. 


270 


CANAL  STRUCTURES 

n 


CANAL  SPILLWAYS  271 

The  capacity  of  the  turnout  will  of  course  be  the  area  of 
its  cross-section  multiplied  by   the  velocity  of   the  water,   or 


5.  Canal  Spillways.  —  Any  large  canal  system  must  for  safety 
be  provided  with  a  number  of  spillways  in  order  to  discharge 
any  surplus  water  it  may  contain,  and  avoid  overtaxing  its 
capacity.  Also  to  discharge  all  the  water,  when  it  becomes 


FIG.  in. — Lateral  Headgates  North  Platte  Valley,  Nebraska. 

necessary  to  quickly  empty  the  canal  in  case  of  a  break  or  a 
threatened  break. 

The  break  of  a  large  canal  discharging  its  great  volume  of 
water  across  the  country,  may  be  very  disastrous,  especially  if 
the  canal  is  on  a  side  hill  high  above  the  country  threatened, 
or  where  the  torrent  crosses  valuable  improved  lands.  Some- 
times these  conditions  are  aggravated  by  treacherous  materials 
in  which  the  canal  is  built,  in  which  case  the  need  of  adequate 
spillways  is  greater.  This  need  is  also  emphasized  where  the 
canal  receives  considerable  local  drainage  into  its  prism,  and  in 


272 


CANAL  STRUCTURES 


ex 

C/2 


CA NA L   SPILLWA  YS 


273 


274 


CANAL  STRUCTURES 


CANAL  SPILLWAYS  275 

case   of   abnormal   rains   may   occasionally   have   its   capacity 
overtaxed. 

A  large  canal  is  usually  provided  with  a  permanent  weir 
in  its  lower  bank  immediately  below  the  headgate,  the  crest 
of  the  weir  being  placed  at  the  elevation  of  normal  water  surface 
of  the  canal  so  as  to  discharge  any  water  that  may  enter  the 
canal  in  excess  of  its  normal  capacity.  Such  a  spillway  will 
not  discharge  any  considerable  quantity  of  water  until  the  water 
stands  considerably  above  its  lip,  and  though  the  discharge 
increases  with  the  rise  of  the  water  surface,  it  does  not  prevent 
such  rise.  The  longer  the  weir,  the  less  the  rise  it  permits. 
Where  it  is  necessary  to  have  a  close  regulation  of  the  level  of 
the  canal  or  basin  controlled  by  a  spillway,  this  may  be  secured 
by  the  provision  of  one  or  more  siphons,  of  the  type  shown  in 
Fig.  115.  The  interior  lip  /  is  located  at  the  level  at  which  it  is 
desired  to  hold  the  water  level.  The  intake  lip  i,  is  located  a 
few  inches  below  the  same  level.  The  outlet  o  is  located  as  far 
below  the  lip  as  circumstances  will  permit,  and  is  submerged 
under  water,  so  that  air  cannot  enter  there.  When  the  water 
rises  above  the  level  of  the  lip  /  it  overflows  into  the  pool  o,  and 
as  it  falls,  it  entrains  the  air  in  the  siphon,  creating  a  partial 
vacuum,  which  is  filled  by  water  forced  in  by  the  outside  pres- 
sure and  this  process  quickly  exhausts  the  air  from  the  siphon, 
and  it  is  soon  discharging  full,  under  the  head  due  to  the  dif- 
ference of  level  between  the  pond  c  and  the  pool  o,  less  the  loss 
of  head  due  to  friction  velocity  head,  and  any  imperfections 
of  construction.  Velocity  and  discharge  are  found  by  the 
following  formulas: 


and 


The  discharge  continues  until  the  decline  of  the  water  surface 
permits  air  to  enter  under  the  lip  i,  in  such  quantities  as  to 
fill  the  siphon.  While  this  device  is  in  action,  the  surface  of 
the  pond  <;,  is  depressed  by  an  amount  due  to  the  entry  head  of 
the  siphon,  and  this  must  be  allowed  for  in  fixing  the  elevation 


276 


CANAL  STRUCTURES 


...,..-. 

SF.CTION  A-A 

FIG.  115. — Plan  and  Section  of  Siphon  Spillway,  on  Canal  in  Colorado  Valley, 

California. 


CANAL  SPILLWAYS 


277 


of  the  intake  lip  i,  otherwise  the  action  of  the  siphon  will  be 
stopped  by  the  entrance  of  air  before  the  pond  is  drawn  down  to 
the  level  desired.  The  coefficient  of  discharge  c  in  such  a  siphon 
is  usually  between  .6  and  .7  when  in  full  operation. 

Where  a  large  canal  is  located  in  rock  or  other  firm  material, 
or  in  good  soil  protected  by  grass  sod  on  very  gentle  slope, 
spillways  are  often  provided  by  so  locating  the  canal  that  the 
water  surface  of  the  full  canal  will  be  just  even  with  the  natural 
ground  level  on  the  downhill  side,  and  omitting  any  bank  for  a 


''8     both  ways^1     — Kk8" 

ao'o-—       — 4^— 

SECTION 

Fro.  1 1 6. — Spillway,  Fort  Shaw  Canal,  Montana. 

considerable  distance.  When  the  water  rises  above  the  normal 
level,  it  flows  gently  over  this  spillway,  in  a  thin  sheet,  without 
destructive  velocity.  Care  must  be  taken  to  prevent  con- 
centration of  the  water  where  it  would  cause  damage. 

Such  a  spillway  costs  practically  nothing,  and  affords  impor- 
tant protection  to  the  canal  against  overtopping  of  banks  where 
breaks  would  be  the  result. 

In  addition  to  those  automatic  spillways  above  described 
which  are  designed  only  to  discharge  surplus  waters,  every  large 
canal  should  be  provided  with  one  or  more  wasteways  through 


278 


CANAL  STRUCTURES 


which  the  canal  can  be  safely  and  quickly  emptied  in  case  of  a 
break.  In  the  absence  of  such  a  provision,  if  the  canal  should 
break  the  water  would  rush  through  the  break  and  continue 
to  do  so  until  the  canal  is  emptied,  after  closing  the  headgates. 
This  might  occupy  several  hours  or  even  days  and  cause  a  large 
amount  of  damage,  both  to  the  canal  itself,  and  to  the  farms 
below  which  lie  in  the  path  of  the  flood  in  seeking  its  way  back 
to  the  river.  Such  a  spillway  is  usually  called  a  wasteway. 
One  such  wasteway  should  be  located  every  10  or  20  miles 
according  to  the  needs.  If  natural  drains  are  crossed  that  can 
carry  safely  the  full  capacity  of  the  canal,  these  furnish  good 
locations  for  wasteways,  and  the  necessary  structure  may  be 


\o)*7>vPresent  Surface 
:f^vV^>^o£  Ground 


Kotes  Structure  to  be  reinforced 
throughout  with  K'sq.  steel 
bars  spaced  12  c's  both  ways 
equidist.  from  concrete  faces 


FIG.  117.— Standard  Sluiceway,  Lower  Yellowstone  Canal,  Montana. 

combined  with  the  structure  required  for  crossing  the  natural 
drainage  channel.  Where  no  such  opportunity  exists,  location 
should  be  sought  where  the  distance  to  the  river  is  short,  and 
it  will  be  necessary  to  provide  a  substantial  lined  channel  to 
the  river,  to  prevent  damage  to  the  lands  traversed. 

At  the  head  of  the  wasteway,  if  possible,  the  bottom  of  the 
canal  should  be  depressed  several  feet  below  the  regular  grade 
of  the  canal  and  the  sill  of  the  spillway  gates  should  be  at  the 
lowest  part  of  the  depression.  This  will  give  the  water  in  the 
wasteway  a  high  velocity,  and  enable  it  to  draw  strongly  from 
both  directions  in  the  canal,  and  thus  empty  it  quickly.  The 
depressed  section  of  the  canal  will  also  serve  to  gather  gravel, 
sand  or  heavy  silt  that  may  be  traveling  on  the  bottom  of  the 
canal,  and  the  wasteway  will  serve  as  a  means  of  sluicing  such 
material  back  to  the  river,  and  thus  perform  a  double  function. 
In  case  the  canal  is  heavily  silt-laden,  it  may  be  advisable  to 


CANAL  SPILLWAYS 


279 


I 


280  CANAL  STRUCTURES 

widen  as  well  as  deepen  the  canal  at  the  head  of  the  wasteway, 
so  as  to  greatly  enlarge  the  canal  section  and  reduce  the  velocity 
of  the  canal  at  this  point,  and  thus  form  a  settling  basin  for  silt. 

A  wasteway  located  within  a  short  distance  below  the  head 
of  the  canal  at  a  point  near  the  river  may  be  so  arranged  that 
when  opened  it  will  produce  a  scouring  velocity  in  the  canal 
clear  back  to  the  headgate,  and  be  made  very  effective  in  ridding 
the  canal  of  accumulations  of  gravel,  sand  and  silt.  In  such 
cases  it  is  well  to  provide  a  set  of  check  gates  in  the  canal  just 
below  the  wasteway,  so  that  by  closing  these,  the  influence 
of  the  wasteway  may  be  concentrated  upon  the  scouring  of  the 
section  above,  and  in  case  of  a  break  in  the  canal  below,  the  check 
gates  may  be  left  open  to  permit  the  emptying  of  that  part 
of  the  canal  also. 

The  gates  of  the  wasteway  should  be  of  some  type  that  can 
be  quickly  opened,  as  they  are  primarily  for  emergency  use. 
For  this  reason  it  is  generally  best  to  provide  some  form  of  power 
for  opening  them.  A  small  turbine  wheel  acting  under  the 
greatest  head  available  from  the  canal  may  be  thrown  instantly 
in  action  by  a  small  valve  operated  by  hand,  or  by  electricity 
from  a  distance,  and  this  wheel,  generating  10  or  20  horse-power, 
may  be  made  to  open  the  gates  very  quickly. 

Where  the  canal  is  located  high  on  a  mountain  side  so  that 
the  great  head  and  steep  slope  will  cause  a  break  to  be  especially 
destructive,  a  series  of  spillways  may  be  electrically  connected 
with  automatic  floats,  so  that  if  the  water  suddenly  rises  or 
lowers  in  the  canal  the  floats  close  the  circuit  and  open  the  spill- 
way, instantly.  A  slide  from  above  may  obstruct  the  canal, 
and  cause  it  to  overflow,  but  if  the  rising  water  opens  the  waste- 
way,  the  canal  may  be  relieved  before  much  harm  is  done. 
Conversely,  if  the  canal  water  surface  is  lowered  by  an  incipient 
break,  this  also  opens  the  wasteway,  and  empties  the  canal 
before  great  damage  is  caused. 

A  type  of  automatic  spillway  that  has  been  successfully 
employed  on  the  Tieton  Canal  in  the  State  of  Washington  is 
described  as  follows: 

On  the  course  of  the  canal  where  a  spillway  was  desired,  a 


CANAL  SPILLWAYS 


281 


282  CANAL  STRUCTURES 

pit  was  built  about  4  feet  below  the  grade  of  the  canal.  A  cast- 
iron  sluicegate  4  feet  by  5  feet  is  operated  by  a  lo-inch  vertical 
turbine  located  just  outside  the  wasteway  pit  with  its  intake 
at  such  an  elevation  that  the  sluicegate  is  entirely  opened  when 
the  receding  water  falls  to  the  center  of  the  intake  opening. 
The  turbine  shaft  is  connected  to  the  gate  shaft  by  a  system 
of  gears.  To  the  turbine  gate  shaft  is  attached  a  drum  around 
which  a  small  cable  is  wound,  having  attached  to  its  end  a 
suspended  weight.  When  the  turbine  gate  is  closed  the  weight 
is  suspended  and  holds  a  projecting  pin  from  the  handwheel 
against  the  magnet  release,  which  is  electrically  connected 
with  floats  placed  at  frequent  intervals  along  the  canal.  Any 
abnormal  change  of  water  surface  in  the  canal  makes  a  connec- 
tion at  the  float  that  causes  the  magnet  to  release;  this  drops 
the  weight,  which  opens  the  turbine  gate  and  starts  the  turbine, 
which  opens  the  wasteway  gates.  To  close  the  gate  the  opera- 
tion must  be  started  by  hand  until  the  water  rises  in  the  pit 
enough  to  enter  the  turbine  intake,  after  which  the  clutch  may 
be  thrown  in  and  the  gate  closed  by  water  power. 

6.  Checks,  Drops,  and  Chutes. — Where  the  slope  of  the 
country  over  which  a  canal  passes  is  greater  than  the  safe  grade 
of  the  canal,  it  becomes  necessary  to  provide  one  or  more 
structures  in  which  the  surplus  grade  can  be  concentrated,  and 
the  canal  transferred  from  a  higher  to  a  lower  elevation  without 
injury  to  the  canal.  Such  a  structure  is  called  a  "  drop " 
and  may  be  either  vertical  or  inclined.  In  the  former,  the  water 
falls  freely,  while  an  inclined  drop  is  one  in  which  the  water  is 
carried  down  an  inclined  pipe,  channel  or  chute,  protected 
against  erosion  by  some  form  of  lining. 

A  Check  is  a  bulkhead  in  a  canal  designed  to  hold  the  water 
above  it  at  a  higher  level  than  it  would  otherwise  stand,  so  that 
when  the  canal  is  carrying  only  part  of  its  capacity,  water  may 
be  taken  into  a  turnout  location  above  the  bottom  of  the  canal. 
It  may  be  desired  at  all  times  to  maintain  the  water  level  above 
the  check  at  a  higher  level  than  below  it,  in  which  case  the  check 
performs  also  the  function  of  a  drop.  Where  this  is  not  the 
case,  and  the  structure  is  simply  a  check  to  be  used  only  when 


CHECKS,   DROPS,   AND  CHUTES 


283 


the  canal  is  running  part  full  and  water  is  being  taken  into  the 
lateral,  it  should  be  so  arranged  that  practically  all  of  the  bulk- 
head can  be  removed  when  not  needed,  so  as  not  to  greatly 
interfere  with  the  flow  of  water  in  the  canal.  During  the  time 
that  the  check  is  in  use,  it  acts  of  course,  as  a  drop;  i.e.,  the  water 
stands  at  a  higher  level  above  than  below  the  check,  and  in  fall- 
ing exerts  an  amount  of  mechanical  energy,  depending  upon  the 
quantity  of  water  and  the  amount  of  the  fall.  Precautions 
must  be  taken  to  prevent  the  destructive  erosion  of  the  earthen 
sides  and  bottom  of  the  canal  just  below  the  check. 


FIG.  120. — Concrete  Drop  with  Water  Cushion,  Truckee-Carson  Canal,  Nevada. 

The  necessity  of  providing  drops  under  various  conditions  is 
a  matter  of  judgment  based  upon  experience.  It  involves  a 
knowledge  of  the  erosive  power  of  the  quantity  of  water  to  be 
handled  at  the  velocity  to  be  expected,  and  the  capacity  to 
resist  erosion  of  the  ground  over  which  the  water  will  pass. 
Some  of  these  elements  are  variable  and  others  may  not  be 
accurately  predicted.  It  is  therefore  unprofitable  to  attempt 
any  exact  rules  or  fine  distinctions.  Some  of  the  earlier  irriga- 
tion works  were  built  without  any  special  provisions  for  excess 
grade,  and  although  erosion  was  certain,  the  rule  seemed  to  be 
"  let  it  cut."  These  have  in  some  cases  resulted  in  gullies, 
which  have  done  no  great  harm.  On  the  other  hand,  some 


284 


CANAL  STRUCTURES 


FIG.  i2i.— Notch  Drop,  Chenab  Canal,  India. 


CHECKS,  DROPS,  AND  CHUTES 


285 


engineers  carry  to  an  extreme  the  theory  that  the  theoretical 
slopes  and  velocities  must  be  exactly  secured  regardless  of  cost. 
The  true  test  of  the  problem  is  the  inquiry  "  What  will  happen 
if  no  provision  is  made?"  If  the  ground  traversed  is  a  loam 
or  sand  to  a  great  depth,  excess  velocities  will  cause  the  eiosion 


FIG.  122. — Crops-section  of  Drop,  Bear  River  Canal. 

of  deep  gullies,  and  the  deposit  of  the  eroded  material  at  some 
point  lower  down.  Even  when  the  channel  is  straight,  slight 
obstructions  or  inequalities  of  material  will  cause  a  tendency 
to  meander,  and  to  undermine  banks  on  the  outside  of  curves. 
If  this  proceeds  it  may  destroy  good  land,  and  load  the  stream 
with  material  to  be  deposited  further  down  to  the  detriment 


286 


CANAL  STRUCTURES 


of  other  property;  it  may  become  necessary  to  provide  expensive 
protection  to  the  banks,  and  this  expense  and  the  damage 
caused  may  exceed  the  cost  of  the  drops  that  should  have  been 
provided  in  the  first  place,  and  may  ultimately  still  be  necessary. 
On  the  other  hand,  cases  occur  where  the  alinement  of  the 
canal  is  straight,  and  where  rock,  shale,  hardpan  or  other 


IJTop  of  bank 


Bottom  width  of  c&r.al **,    Riprap  canal  for      [-Top  of  bank 

!'     varying  distances 


ELEVATION 
FIG.  123. — Notch  Drop,  Interstate  Canal,  Nebraska-Wyoming. 

indurated  material  occurs  a  short  distance  below  the  surface, 
that  will  resist  erosion,  and  may  be  utilized  to  save  expense  in 
the  provision  of  structures  and  their  subsequent  maintenance. 
The  hard  material  may  be  irregular  in  its  occurrence  and  quality, 
and  when  it  is  reached  by  the  water,  erosion  is  checked,  and  a 
steeper  grade  is  soon  established  through  the  hard  material 


CHECKS,  DROPS,  AND  CHUTES 


287 


which  becomes  permanent.  In  this  way  the  surplus  grade  is 
taken  up,  and  with  some  bank  protection,  stability  is  secured. 
Where  the  country  has  considerable  slope  it  may  be  neces- 
sary to  provide  hundreds  of  drops  in  the  lateral  system,  and  it 
thus  becomes  important  to  decide  on  the  most  effective  and 
economical  design  as  a  standard  for  each  grade,  character  of 
soil  and  quantity  of  water.  Where  the  slope  is  considerable 
and  the  soil  sandy,  careful  consideration  should  be  given  to 
lining  the  canal  with  concrete  to  prevent  erosion,  instead  of  the 
construction  of  drops.  The  high  velocities  thus  secured  will 

m/3"x  4" 


2  x!2' 


*#•'. '•<:•': •' Gruvel  FiUin- v^ 


-[          [  •  _^J.L---    '•    .      •         , 

F^2"x  €  2"*  &*j$ 


2  x!2 


x!2 


FIG.  124. — Timber  Drop,  Lower  Yellowstone  Laterals,  Montana. 

permit  reduction  of  the  cross-section  of  the  canal  and  thus  save 
in  excavation,  besides  eliminating  the  cost  of  the  drops;  and 
though  the  lined  channel  may  be  more  expensive,  it  may  still  be 
justified  on  account  of  the  saving  of  water  and  in  maintenance 
cost,  both  of  which  are  important. 

A  cheap  and  efficient  drop  on  a  small  lateral  is  formed  by 
excavating  the  channel  for  the  necessary  distance  on  a  grade 
of  three  or  four  to  one,  lining  it  with  concrete,  and  providing  a 
depressed  basin  at  the  foot  of  the  slope  to  receive  and  check 
the  rushing  water.  The  lower  side  of  this  basin  should  be 
vertical  to  form  an  effective  check  to  the  water.  A  small  cutoff 


288 


CANAL  STRUCTURES 


CHECKS,  DROPS,  AND  CHUTES 


289 


wall  should  be  provided  at  the  upper  edge  of  the  lining  where 
the  water  reaches  it,  to  prevent  under-cutting.  Such  simple 
drops  have  been  successfully  used  in  light  soils  by  the  U.  S. 
Reclamation  Service,  and  are  very  cheap,  requiring  very  little 
forming  for  the  stilling  basin,  and  none  at  all  for  the  lining. 

For  large  volumes  of  water  more  elaborate  structures  are 
required.  These  are  sometimes  of  wood,  but  are  more  per- 
manent and  reliable  when  built  of  concrete. 


FIG.  126. — Cylinder  Drop  on  Franklin  Canal,  Rio  Grande  Valley,  Texas. 


The  notched  drop,  introduced  in  India  and  employed  to 
some  extent  in  this  country,  has  the  crest  of  the  fall  surmounted 
by  a  weir  with  a  series  of  notches  with  their  bases  level  with  the 
canal  bed,  and  the  top  of  the  weir  at  or  above  the  full  supply 
level.  The  notches  are  designed  wider  at  top  than  at  base,  so 
as  to  discharge  at  any  given  level,  the  same  amount  of  water 
that  the  canal  carries  at  that  level  at  normal  velocity,  and  thus 
prevent  undue  fluctuation  of  velocity  as  the  volume  of  water 


290  CANAL  STRUCTURES 

varies.  Below  each  notch  is  provided  a  semicircular  horizontal 
lip  or  bracket  to  receive  the  falling  water  and  spread  it  out  into 
a  semicircular  sheet.  This  has  a  tendency  to  dimmish  the  action 
of  the  water  on  the  banks  below. 

The  U.  S.  Reclamation  Service  has  used  a  novel  form  of 
drop  in  the  Rio  Grande  Valley,  consisting  of  a  concrete  structure 


FIG.  127. — Series  of  Concrete  Drops  on  South  Canal,  Uncompahgre  Valley, 

Colorado. 


in  which  the  water  is  controlled  by  balanced  cylinder  gates 
which  can  be  adjusted  to  such  opening  as  will  produce  the 
proper  velocity  to  prevent  scour  and  deposit  of  silt  at  all  stages 
of  canal  flow.  See  Fig.  126. 

7.  Protection   Against    Erosion. — The    tendency    to    erosion 
arises  from  three  main  causes: 

1.  The  impact  of  the  water  on  the  bottom  of  the  canal  as 
it  falls  from  the  higher  to  lower  level.     This  usually  requires 
some  sort  of  paving. 

2.  The   increased   velocity   generated   by   the   surplus    fall, 


PROTECTION  AGAINST  EROSION 


291 


which  if  not  somehow  checked  will  persist  for  some  distance 
down  the  canal  and  erode  its  banks.  This  may  be  counter- 
acted by  providing  a  stilling  pool  at  the  foot  of  the  drop  with 
depressed  bottom  and  larger  section  than  the  regular  prism 
of  the  stream,  in  which  the  energy  is  dissipated  in  surges  and 
eddies,  and  from  which  the  water  flows  away  at  normal  velocity. 
3.  The  waves  produced  by  the  commotion  of  the  falling 
water,  and  which  generally  persist  for  some  distance  down  the 


Fr«.  128. — Concrete  Chute  and  Stilling  Basin,  Boise  Valley,  Idaho. 

canal  in  spite  of  elaborate  control  of  the  velocity  of  the  water. 
This  generally  requires  paving  or  other  protection,  of  the  bank 
for  30  to  50  feet  below  the  drop,  or  in  very  light  soil,  a  still 
greater  distance.  This  protection  may  be  a  lining  of  concrete 
or  of  grouted  rip-rap,  or  other  form  of  paving.  Open  rip-rap 
without  mortar  soon  fails  in  light  soils  by  the  washing  out  of 
soil  through  the  cracks.  In  many  cases  sage  brush  held  in  place 
by  stakes  and  wire  has  been  successfully  used. 


292  CANAL  STRUCTURES 

The  amount  and  character  of  protection  necessary  depends 
upon  the  quantity  of  water  falling,  the  amount  of  the  fall,  and  the 
character  of  the  material  in  which  the  drop  occurs.  Unless 
the  latter  is  rock  or  very  firm  gravel  or  hardpan,  some  paving 
or  other  artificial  protection  is  always  necessary.  The  size  and 
depth  of  the  stilling  pool  has  been  much  discussed,  but  engineers 
are  not  agreed  upon  any  general  rule  to  govern  these  points. 
The  best  practice  is  to  provide  a  pool  depressed  from  i  to  3  feet 
below  the  bottom  of  the  canal  below  the  drop,  and  having  a 
cross-section  from  50  per  cent  greater  than  the  normal  water 
prism,  to  three  times  as  great,  varying  between  these  limits 
according  to  the  three  factors  above  mentioned,  namely,  the 
height  of  fall,  the  quantity  of  water,  and  the  character  of  soil 
in  which  the  drop  occurs. 

In  some  cases  it  is  necessary  to  carry  the  water  down  a  long 
slope  requiring  either  a  series  of  drops  or  a  long  chute,  consisting 
of  a  lined  channel  with  a  stilling  basin  at  the  bottom.  The 
choice  between  these  types  will  depend  mainly  upon  the  cost, 
but  if  properly  built  the  maintenance  of  a  chute  is  generally 
less  than  that  of  the  vertical  drops  that  would  take  its  place. 

The  inclined  drop  or  chute  consists  essentially  of  an  inlet 
structure,  a  trough  to  conduct  the  water  down  the  hill,  and  a 
pool  at  the  bottom  to  receive  the  water  and  destroy  its  accumu- 
lated energy.  The  transition  from  the  canal  to  the  drop  must 
be  provided  with  numerous  and  deep  cutoff  walls  for  the  wing- 
walls,  floor  and  sides,  carefully  puddled  in,  to  prevent  percolation 
of  water  along  the  structure.  Where  the  water  enters  the 
trough  control  gates  should  be  provided.  A  short  distance 
below,  the  trough  converges  to  a  narrow  channel  to  correspond 
to  the  increased  velocity,  which  may  reach  40  or  50  feet  per 
second.  Cutoff  walls  must  be  provided  at  frequent  intervals 
under  the  trough,  and  great  precautions  must  be  taken  to  prevent 
erosion  under  the  trough,  either  by  rainfall  or  by  leakage  from  the 
structure,  as  the  steep  hillside  will  favor  rapid  and  destructive 
erosion  if  an  opportunity  occurs. 

Trouble  was  encountered  on  the  Boise  Project  of  the  Reclama- 
tion Service  with  the  spilling  of  water  over  the  sides  of  the  stilling 


DRAINAGE  CROSSINGS  293 

basins  at  the  end  of  concrete  chutes  and  investigation  was  made 
to  find  a  remedy. 

The  cause  of  the  trouble  apparently  was  that  in  designing 
the  structure  no  allowance  was  made  for  the  great  amount  of 
air  carried  into  these  basins  with  the  water.  Eleven  structures 
were  investigated  and  the  remedy  generally  adopted  was  to 
raise  the  sides  and  cover  the  basin.  The  investigations  seem 
to  indicate  that  in  designing  stilling  pools,  consideration  should 
be  given  to  the  increased  volume  of  the  discharge  due  to  mixture 
of  air  with  water.  For  velocities  from  15  to  40  feet  per 
second,  the  increased  bulk  is  estimated  to  be  from  15  to  35 
per  cent. 

The  pool  or  check  basin  at  the  bottom  of  the  chute  must 
be  of  massive  construction  to  receive  the  shock  of  the  rushing 
waters,  and  stop  it  without  injury.  An  excellent  form  for  such 
a  check  basin  is  one  on  the  Sulphur  Creek  wasteway  on  the 
Yakima  Project  in  Washington,  which  is  designed  to  receive 
and  stop  a  stream  of  500  cubic  feet  per  second  flowing  at  a 
velocity  of  about  25  feet  per  second.  This  structure  is  of 
concrete,  rectangular  in  plan  14  by  18  feet,  by  18  feet  high. 
The  water  comes  in  at  one  end  of  the  box  near  the  top,  and 
escapes  through  two  rectangular  openings  in  the  sides,  each 
i2j  by  4  feet.  The  water  plunges  into  the  basin  and  dissipates 
its  energy  by  impact  on  the  water  already  there,  and  is  turned 
practically  through  3  right  angles  before  it  can  escape.  This 
structure  accomplishes  its  object  satisfactorily,  as  the  water 
flows  quietly  down  the  unlined  canal  without  erosion. 

Deep  gullies  are  unsightly  and  may  be  dangerous  if  very 
deep  with  precipitous  banks,  and  it  requires  important  saving 
of  expense  to  justify  the  omission  of  sufficient  drops  to  consume 
the  excess  grade. 

Where  the  drop  can  be  located  in  rock  it  may  be  unnecessary 
to  provide  any  special  protection  to  the  bottom  or  sides. 

8.  Drainage  Crossings. — Where  a  canal  location  intercepts 
a  natural  drainage  line  or  torrent,  as  it  is  sometimes  called,  it 
is  necessary  to  decide  what  disposition  to  make  of  the  drainage 
water  that  may  be  expected,  in  order  that  it  may  not  damage 


294 


CANAL  STRUCTURES 


DRAINAGE  CROSSINGS 


295 


the  canal.     There  are  four  possible  methods  of  dealing  with'  such 
problems,  each  of  which  is  suitable  to  a  certain  class  of  cases. 

i.  The  drainage  may  be  received  into  the  canal,  in  cases 
where  it  is  small  in  amount  and  the  canal  is  large. 


_.ZJT_.  -    -x -(,0 —     -x- 


FIG.  131. — Elevation  and  Cross-section  of  Iron  Flume  on  Corinne  Branch,  Bear 

River  Canal,  Utah. 

2.  The  canal  may  be  carried  over  the  drainage  channel  in  a 
flume,  or  upon  an  embankment  provided  with  a  culvert  through 
which  the  drain  water  passes  under  the  canal. 

3.  The  canal  may  be  carried  under  the  ravine  in  an  inverted 
siphon  or  pressure  pipe,  or  the  drainage  may  be  conducted  over 
the  canal  in  a  broad  flume  called  a  superpassage. 


296 


CANAL  STRUCTURES 


4.  The  drainage  may  be  intercepted  by  a  diversion  dam 
and  canal  and  conducted  along  and  parallel  to  the  canal,  to  a 
point  where  sufficient  drainage  is  concentrated  to  justify  the 
provision  of  one  of  the  structures  above  mentioned. 


Span  varies  from  14  to  30 


-Irrf3355t 

tf-^rp^rfr.  j     -jjl 

III. 

1-1-4  4-  1   '  1- 

-•--+-4-4- 

1 

Span  s      Span  s 

- 

.^44-j-|4rf 

'--t--i-irji-Izi-i  :±- 

[ttitbJ 

Kfi 

' 

*-14' 

10' 
13' 

70"  24'  8'0> 
8'0'  20'  8'8' 
i)'o'  28'  9'*" 

C 

* 

•H- 

Upper  girder"^ 
bars  over      Kf. 

*•   ELEVATION  OF  FLUME,- 

— 

7  4 



is 

supports  only/f 

,  6varies 

from  4  'to  1 

I—  > 

^Longitudinal 
rs  ^Rl2'  c.  to  c. » 


May  be  used  for  outlet  when  " 
desirable  .| 

Bars  in  Floor 
placed  in  ccntt 


SECTION  A-B 
Method  of  bonding 
flume  to  inlet 


VERTICAL  SECTION  AT  COLUMN     ELEVATION  OF  COLUMI 

Top  of  column  base 


=    ,      .I     . 

6  =  10        2  9'x  13  0 
3'o'x  15  0' 


PLAN  OF  COLUMN  BASE 


J-..JI 

LONGITUDINAL  SECTION  OF  INLET 

FIG.  132. — Standard  Reinforced  Concrete  Flume,  Reclamation  Service. 

Wherever  a  large  canal  is  built  on  ground  sufficiently  sloping 
so  that  no  bank  is  required  on  the  uphill  side,  some  rain  water 
will  inevitably  flow  into  the  canal  from  the  surface  of  the  ground. 
From  the  admission  of  such  rain  water,  it  is  but  a  step  to  the 
admission  of  small  drainage  channels  which  seldom  carry  water, 


DRAINAGE  CROSSINGS 


297 


oint 


and  carry  but  little  at  any  time.  Where  it  is  necessary  to  admit 
considerable  quantities  of  surface  water  to  the  canal,  its  safety 
may  be  protected  by  providing  in  the  vicinity  a  spillway  of  one 
of  the  types  described  in  Art.  5. 

Even  when  the  water  brought  in  may  be  thus  taken  care  of, 
the  admission  of  drainage  to  the  canal  is  often  objectionable 
because  such  drainage  usually  4-Square 
:arries  sediment  and  detritus 
which  may  be  expensive  to  re- 
move. Care  must  be  taken  in 
all  cases  to  protect  the  side 
of  the  canal  where  drainage 
enters,  against  the  erosion  of 
gullies  which  destroy  the  sym- 
metry of  the  canal,  and  fill  it 
with  detritus.  This  protection 
may  consist  of  a  short  concrete 
retaining  wall,  over  which  the 
drain  water  falls  into  the  canal. 
The  provision  of  a  combined 
wasteway  and  settling  basin 
with  bottom  opening  for  sluic- 
ing sediment,  may  justify  the 
admission  to  the  canal  of  much 
drainage  in  the  vicinity  other- 
wise inadmissible. 

Cases  sometimes  occur  where 
the  collection  of  drainage  water 

is  one  of  the  important  functions  ! | 

of  a  canal,  the  object  being  to  FIG.  133.— Circular  Reinforced  Con- 
increase  the  water  supply  above  crete  Flume  and  Trestle,  Tieton 

•  ill          rr^i  Canal,  Washington. 

that   otherwise   available.     The 

water  supply  thus  obtained  is  usually  so  irregular  that  a  storage 
reservoir  is  necessary  to  utilize  the  full  benefit  of  such  supplies, 
and  it  thus  becomes  especially  important  to  provide  for  ridding 
the  canal  of  sediment  brought  in  with  the  drainage  to  avoid 
filling  the  reservoir  with  solid  matter  and  destroying  its  useful- 


298 


CANAL  STRUCTURES 


ness.     This  may  best  be  done  by  means  of  settling  basins  with 
bottom  opening  for  sluicing  purposes  as  described  in  Art.  5. 


FIG.  134. — Headworks  of  Cavour  Canal,  Po  River,  Italy. 


FIG.  135. — Brick  Aqueduct,  Carrying  Cavour  Canal,  Po  Valley,  Italy. 

In  all  cases  the  drainage  to  be  admitted  should  be  carefully 
estimated,  especially  as  to  its  probable  maximum  volume,  and 
provision  made  for  such  maximum  with  a  considerable  margin 


FLUMES  299 

of  safety.  The  lower  bank  of  the  canal  must  be  of  ample  height 
and  thickness,  and  must  be  rigidly  inspected  for  the  works  of 
burrowing  animals,  so  that  a  sudden  rise  in  the  water  level 
shall  not  disclose  a  hole  to  lead  water  through  the  bank  and 
cause  disaster. 

9.  Flumes. — Where  the  drainage  line  intercepted  is  in  a 
ravine  or  canyon  of  moderate  depth,  but  well  below  the  grade  of 
the  canal,  the  latter  may  be  carried  across  in  a  flume.  This 
may  best  be  of  concrete,  especially  if  very  large,  but  on  account 
of  the  high  cost  of  the  concrete  structure,  flumes  are  more  often 
built  of  steel,  upon  wooden  trestles,  or  entirely  of  wood.  These 
are  more  expensive  in  maintenance,  and  will  require  renewal 
of  the  wooden  parts  in  from  10  to  20  years,  even  when  well 
cared  for.  In  any  case  the  trestle  bents  should  be  founded  upon 
concrete  or  rock,  and  contact  between  wood  and  earth  at  any 
point  entirely  prevented,  to  avoid  quick  decay.  The  most 
common  form  for  wooden  flumes  is  a  rectangular  box,  and  should 
provide  for  a  water  depth  of  about  half  the  width,  as  this  gives 
the  maximum  value  of  r  in  the  formula  and  consequently  the 
maximum  velocity  and  capacity.  For  the  same  reason,  the 
inside  of  the  flume  must  be  made  as  smooth  as  possible.  The 
lumber  should  be  planed,  and  placed  longitudinally,  so  as  to 
have  the  minimum  number  of  joints  across  the  course  of  the 
water,  and  every  care  taken  to  avoid  friction  or  obstruction  to 
the  flow. 

The  flume  must  be  so  constructed  that  it  is  firmly  held  against 
the  tendency  to  spread  which  will  develop  when  filled  with 
water.  This  is  accomplished  by  means  of  the  sills  at  the  bottom, 
and  the  sides  may  be  held  at  top  by  means  of  braces  across  the 
top,  either  of  timber  or  of  heavy  wire,  or  the  sides  may  be 
braced  by  inclined  studs  placed  upon  extensions'  of  the  sills. 
A  standard  form  of  box  flume  is  shown  in  the  drawing,  Fig.  138. 

The  lumber  forming  the  box  of  the  flume  must  be  carefully 
milled  so  as  to  fit  well,  and  some  measures  must  be  proviqled 
to  make  the  cracks  water-tight.  This  is  sometimes  secured  by 
milling  a  small  bead  on  one  or  both  edges  of  the  lumber  which 
can  by  reasonable  pressure  be  made  to  form  a  tight  seam.  Very 


300 


CANAL  STRUCTURES 


FLUMES 


301 


302 


CANAL  STRUCTURES 


effective  sealing  may  be  secured  by  caulking  with  oakum.  To 
facilitate  the  caulking  process  the  lumber  may  be  slightly 
beveled  on  one  edge,  thus  leaving  a  small  opening  on  the  inside 
of  the  crack  for  the  insertion  of  the  oakum.  The  caulking  may 


'10'- 


FIG.  138. — Cross-section  of  San  Diego  Flume,  California. 

require  repetition  every  spring   for    two  or    three  years  after 

which  longer  intervals  may  be  found  permissible. 

Another  means  of  closing  the  seams  of  the  box  flume  is  by 

inserting  asphalt  or  coal  tar,  and  holding  it  in  place  by  means 

of  a  batten  along  the  seam, 
or  a  similar  end  may  be 
secured  by  milling  the 
lumber  so  as  to  admit 
and  hold  the  sealing  ma- 
terial. 

An  objection  to  the  use 
of  battens  on  the  bottom  of 
the  flume  is  that  if  fastened 
to  both  planks  forming  the 
seam,  the  shrinkage  that 
is  likely  to  follow  when 

FIG.  139.— Cross-section  of  Stave  and  Binder     water     is     turned     out     of 
Flume,  Santa  Ana  Canal,  California.  the     flume     Will     split     the 

batten    and     cause     leaks 

with  no  convenient   means   of   repair    except   by  replacing  the 
batten. 


FLUMES 


303 


Coal  tar  or  asphalt  should  in  use  be  applied  hot  and  preferably 
in  warm  weather,  so  that  all  cavities  may  be  penetrated  before 
the  asphalt  solidifies. 

Another  serviceable  form  of  wooden  flume  is  the  half  circle, 
formed  of  wooden  staves  supported  by  iron  or  steel  rods,  the 
ends  of  which  are  held  by  stringers.  These  rods  are  fastened 
by  nuts  which,  when  screwed  up  cinch  the  staves  and  close  all 
cracks  tightly.  This  means  can  be  used  each  year  to  take  up 
the  shrinkage  of  staves  and  keep  the  flume  tight.  The  necessity 


-^         1  Steel  Rods  spaced  6  ce 


The  longitudinal  reinforcing  rods  of 
the  flume  are  to  be  carried  W)"iuto 
the  concrete  face  of  approach 


'Floor  of  flume 


SCALE  OF  FEET 


10123456789     10 


FIG.    140. — Section    through    Reinforced    Concrete  Aqueduct,   Interstate    Canal, 
Nebraska-Wyoming. 

of  caulking  may  thus  be  avoided,'  if  the  staves  are  carefully 
milled,  and  this  constitutes  an  important  advantage  of  the 
circular  over  the  rectangular  form  of  flume.  The  screw  threads 
must  be  kept  well  greased  to  prevent  rust,  and  keep  them 
available  for  the  annual  cinching.  When  properly  built  and 
maintained  such  a  flume  is  generally  more  satisfactory  than  the 
box  flume. 

Steel  Flumes. — Closely  similar  to  the  circular  wooden  flume 
is  the  steel  flume  supported  on  wooden  trestles.  The  metal 
takes  the  form  of  the  half  circle,  and  is  supported  by  iron  rods. 
The  sheets  of  steel  are  purchased  in  standard  sizes,  the  largest 


304 


CANAL  STRUCTURES 


FLUMES  305 

obtainable  being  usually  10  feet  in  length.  A  half -circular  flume 
formed  of  such  sheets  has  an  area  of  31.76  square  feet,  or  leaving 
i  foot  freeboard,  about  25  square  feet  of  waterway.  If  a  capac- 
ity greater  than  this  is  desired,  it  becomes  necessary  to  duplicate 
the  flume,  or  adopt  some  other  type.  The  transverse  joints 
have  been  formed  in  various  ways  more  or  less  efficient,  the 
most  essential  requirement  being  that  they  present  the  least 
possible  obstruction  to  the  flow  of  water,  and  hence  be  flush 
with  the  surface  of  the  flume. 

If  the  flume  is  over  50  feet  in  length,  it  should  be  provided 
with  joints  that  will  absorb  expansion  and  contraction  due  to 
temperature  changes. 

If  the  flume  can  be  conveniently  built  in  cold  weather,  while 
the  metal  is  contracted,  fewer  contraction  joints  will  be  required 
than  if  placed  in  summer. 

The  metal  sheets  should  be  galvanized  and  after  construction 
the  waterway  should  be  treated  with  two  coats  of  tar  paint, 
the  first  of  water-gas  tar  and  the  second  of  coal  tar. 

If  the  flume  carries  sand  or  gravel  this  will  quickly  wear 
through  any  protective  coating,  such  as  tar  or  zinc,  and  leave 
the  iron  exposed  to  rust,  so  that  it  is  very  important  to  eliminate 
sand  or  gravel  if  present.  This  may  be  done  by  providing  a 
settling  basin  and  sluice  gate  at  the  upper  end  of  the  flume, 
either  in  the  flume  itself  or  above  its  entrance.  With  such  a 
provision,  and  careful  attention,  a  metal  waterway  may  be 
expected  to  last  much  longer  than  a  wooden  one. 

All  parts  of  the  flume  should  be  amply  heavy,  so  that  its  load 
will  not  cause  notable  deflection  and  develop  leaks.  It  is  of 
prime  importance  that  the  lumber  be  well  seasoned  so  that  it  will 
not  seriously  warp  and  shrink  after  construction.  The  life  of  the 
wood  may  be  somewhat  increased  by  some  form  of  treatment 
by  antiseptic  preparations.  The  cheapest  of  these  is  a  bath 
in  hot  crude  petroleum.  This  should  be  sufficiently  prolonged 
so  as  to  permit  the  escape  of  all  confined  air,  and  its  replacement 
with  oil. 

Treatment  with  creosote  or  zinc  oxide  as  practiced  with 
railroad  ties  prolongs  the  life  of  the  wood,  but  where  it  is  kept 


306 


CANAL  STRUCTURES 


FLUMES 


307 


L 


308 


CANAL  STRUCTURES 


away  from  earth,  the  benefits  derived  from  treatment  are  hardly 
commensurate  with  its  cost.  Some  benefit  may  be  derived  by 
treating  the  structure  after  completion  with  a  wash  of  any  of  the 
common  preparations  from  petroleum  or  coal  tar;  or  of  the 
more  durable  paints.  Painting  lumber  not  seasoned  does  more 
harm  than  good. 

Care  should  be  taken  to  prevent  contact  with  earth,  which 
hastens  decay  whenever  it  occurs.  Footings  and  mud  sills  may 
generally  be  built  of  concrete. 

10.  Behavior  of  Various  Metals  in  Presence  of  Alkali. — Cer- 
tain preparations  of  iron  and  steel  have  shown  resistance  to  the 


IP     ,  itip 


HALF  SECTION 


SCALE  OF  FEET 
10  20 


FIG.  144. — Half  Longitudinal  Section,  Reinforced  Concrete  Aqueduct,  Interstate 
Canal,  Nebraska-Wyoming. 


attacks  of  acids  as  shown  by  standard  tests,  but  western  waters 
are  often  alkaline,  and  resistance  to  alkali  is  a  different  problem. 
The  U.  S.  Reclamation  Service  has  made  a  series  of  experiments 
to  test  the  virtues  of  various  metals  in  the  presence  of  alkali 
such  as  occurs  in  many  western  soils. 

The  results  of  these  tests  as  reported  by  the  project  managers 
on  three  different  projects  are  shown  in  the  following  table. 
All  the  sheets  were  planted  in  alkaline  mud,  the  tests  samples 
being  side  by  side,  under  conditions  as  similar  as  possible.  The 
results  speak  for  themselves: 


BEHAVIOR  OF   VARIOUS  METALS 


309 


TABLE  XXXI.— METAL  SHEETS  IN  ALKALINE  SOILS 


Material. 

Weight, 
Ounces. 

Length 
of  Test, 
Years. 

Loss, 
Ounces. 

Loss, 
Per  Cent. 

Project. 

Toncan  metal,  galvanized  .  . 

81.75. 

4 

I  .00 

1.36 

Sun  River 

Ingot  iron,  galvanized  

88.0 

4 

I  .00 

1.14 

(  i 

Mild  steel,  galvanized  

79-50 

4 

I  .00 

1.26 

«  c 

Toncan  metal,  ungalvanized. 

73-75 

4 

5-50 

7.46 

" 

Ingot  iron,  ungalvanized.  .  .  . 

78.50 

2 

2.25 

2.87 

1  1 

Mild  steel,  ungalvanized..  .  . 

75-50 

4 

4-50 

5-96 

(  I 

Toncan  metal,  galvanized.  .  . 

81.00 

a* 

•50 

.60 

Uncompahgre 

Ingot  iron,  galvanized  

89.00 

a* 

I  .00 

I  .  IO 

i  ( 

Mild  steel,  galvanized  

81.00 

a* 

1  .00 

1  .  20 

i  e 

Toncan  metal,  ungalvanized. 

73-50 

a* 

4.50 

6.  10 

(  i 

Ingot  iron,  ungalvanized  .  .  . 

81.50 

2| 

4-50 

5-50 

(  i 

Mild  steel,  ungalvanized..  .  . 

76.00 

2| 

3-oo 

4.00 

" 

Toncan  metal,  galvanized.  .  . 

82.50 

a* 

2.50 

3-03 

Belle  Fourche 

Ingot  iron,  galvanized  

91  .00 

at 

2.50 

2-75 

(  ( 

Mild  steel,  galvanized  

81.00 

at 

I  .  20 

i  .  48 

(  t 

Toncan  metal,  ungalvanized. 

78-5 

at 

5.10 

6.50 

(( 

Ingot  iron,  ungalvanized  .  .  . 

83-5 

at 

4-70 

5-63 

<  i 

Mild  steel,  ungalvanized..  .  . 

76.0 

aj 

2.20 

2.90 

The  most  striking  result  brought  out  by  these  tests  is  the 
immense  advantage  of  galvanized  sheets  over  those  of  plain 
metal.  It  is  also  made  clear  that  none  of  the  different  special 
preparations  tested  have  any  great  or  uniform  advantage  over 
any  others. 

Where  the  cost  is  not  too  great,  flumes  should  be  constructed 
of  concrete,  as  this  will  generally  form  a  structure  of  permanent 
character  if  properly  built.  If  the  waterway  to  be  crossed  is 
large  and  the  canal  also  large,  such  a  flume  becomes  a  very 
heavy  structure,  and  must  be  very  solidly  founded  to  prevent 
settlement  and  failure.  The  most  desirable  foundation  of 
course  u  rock,  although  indurated  sand,  clay,  shale  or  gravel 
may  be  depended  upon  if  the  foundation  is  spread  enough  to 
prevent  dangerous  unit  stresses.  A  foundation  of  shale  some- 
times contains  seams  of  soluble  salts,  which  unless  well  protected, 
may  later  dissolve  and  cause  trouble. 

In  several  localities  where  the  surface  is  underlain  by  shale, 
the  structures  founded  thereon,  and  even  the  lining  of  canals 


310 


CANAL  STRUCTURES 


FlG.   145. — Reinforced   Concrete   Aqueduct,    Spring   Canyon,   Interstate   Canal, 

Nebraska-Wyoming. 

• 


FIG.  146. — Concrete  Flume,  Spanish  Fork  Valley,  Utah,  showing  Warped  Transi- 
tion from  Canal  to  Flume. 


BEHAVIOR  OF   VARIOUS  METALS 


311 


I 

I 

I 


312 


CANAL  STRUCTURES 


m 


& 


FIG.  148.— Continuous  Wood-Stave  Pressure  Pipe,  Idaho  Irrigation   Company' 

Canal. 


BEHAVIOR   OF    VARIOUS  METALS 


313 


have  settled  and  cracks  have  formed,  causing  leakage  and  other 
annoyance.  This  seems  to  be  due  to  the  water  penetrating 
the  indurated  shale  and  removing  a  portion  of  the  soluble  salts 


FIG.  149. — Elevation  and  Cross-section  of  Nadrai  Aqueduct,  Lower  Ganges  Canal, 

India. 

from  the  seams  and  crevices  which  they  fill.  In  many  places 
where  canals  are  constructed  through  hard  shale  requiring 
powder  to  loosen,  they  have  settled  badly  when  water  was 


314  CANAL  STRUCTURES 

turned  through  them.  In  a  few  instances  the  shale  has  swelled, 
causing  the  bottom  to  bulge. 

One  of  the  most  important  of  the  necessary  provisions  is  to 
make  safe  allowance  for  changes  of  temperature  which  cause 
expansion  and  contraction  of  the  flume  structure.  This  is  apt 
to  cause  openings  between  the  concrete  ends  and  the  earth 
filling,  and  to  start  a  leak  which  will  rapidly  enlarge  under  the 
high  velocities  generated,  and  cause  a  break  difficult  to  repair, 
and  more  difficult  to  guard  against  in  future. 

The  problem  is  to  devise  a  junction  between  the  concrete 
and  earth  that  will  permit  movement  without  leakage.  Such 
a  junction  has  been  successfully  used  at  the  termini  of  the  Spring 
Canyon  flume  on  the  North  Platte  project,  by  means  of  suc- 
cessive layers  of  canvas  saturated  with  tar,  to  make  it  imper- 
vious. 

ii.  Culverts. — Where  the  grade  of  the  canal  is  high  enough 
to  permit  its  passage  over  the  intercepted  drainage  channel, 
and  the  volume  of  the  torrent  to  be  intercepted  is  not  too  great, 
the  canal  may  be  carried  across  in  an  earth  fill,  and  the  drainage 
water  carried  through  the  fill  in  a  cast-iron  pipe,  or  if  too  great 
for  this,  in  a  concrete  conduit.  The  fill  must  be  carefully  con- 
structed, observing  all  the  rules  of  earth  dams  as  to  water  tight- 
ness and  careful  connection  at  the  ends  with  the  natural  banks, 
and  at  the  bottom  with  good  material  for  foundation. 

The  culvert  should  have  flaring  approaches  to  conduct  the 
water  gently  into  the  conduit,  and  these  should  be  founded 
deeply  and  provided  with  wingwalls  to  prevent  percolation 
around  them.  The  culvert,  whether  of  iron  or  concrete,  should 
be  provided  with  several  cutoff  collars  passing  entirely  around 
them,  and  well  puddled  in  with  good  material  at  least  one- third 
of  which  should  be  clay.  The  central  portion  of  the  fill,  and  all 
that  portion  adjacent  to  the  canal  water  section  should  be  wetted 
and  rolled,  or  carefully  puddled,  to  the  end  that  no  percolation 
from  the  canal  shall  endanger  the  fill.  Culverts  are  sometimes 
made  of  wood,  but  this  is  not  permanent  work,  as  the  wood  in 
contact  with  moist  earth  does  not  last  long.  Small  culverts 
may  be  made  of  galvanized,  corrugated  iron  where  the  fill  is 


CULVERTS 


315 


not  too  high  for  this,  but  care  must 
be  taken  to  allow  for  the  retarding 
influence  of  the  corrugations,  and  to 
provide  all  the  precautions  necessary 
with  cast-iron  pipes. 

Where  a  large  canal  intersects  a 
large  drainage  line  so  nearly  at  grade 
that  it  is  not  practicable  to  carry 
the  canal  over  the  drainage,  the 
canal  may  be  carried  below  grade  in 
a  pressure  conduit,  or  the  torrent 
may  be  carried  over  the  canal  in  a 
large  flume,  which  is  called  a  "  super- 
passage." 

The  superpassage  must  be  amply 
large  with  a  wide  margin  of  safety 
to  discharge  the  largest  torrent  that 
the  drainage  line  may  bring,  without 
danger  of  overtopping  and  should  be 
carried  upstream  on  a  grade  of  not 
less  than  i  in  5000,  a  sufficient  dis- 
tance to  intersect  the  natural  grade 
of  the  torrent,  pass  under  it  to  a 
depth  of  several  feet,  and  terminate 
in  a  cutoff  or  curtain  wall  carried 
considerably  deeper  unless  rock  or 
impervious  or  indurated  material  is 
encountered  sooner.  No  exact  rules 
can  be  laid  down  except  that  the 
upper  end  of  the  bottom  and  sides  of 
the  superpassage  must  be  so  bonded 
and  incorporated  with  the  bottom 
and  sides  of  the  torrential  channel 
as  to  leave  no  danger  of  the  water 
working  between  and  passing  under 
or  around  the  structure,  and  it  must 
be  remembered  that  these  torrents 


316 


CANAL  STRUCTURES 


a 


CULVERTS 


317 


in    flood,  often    erode    under    their    channels    far    below    the 
customary  bed,  and  fill  them  again  on  the  declining  flow. 

The  superpassage  must  deliver  the  torrent  to  its  natural 
channel,  or  other  safe  channel  in  a  manner,  and  at  a  distance 


FIG.  152.— Inlet  to  Rawhide  Siphon,  Interstate  Canal,  Nebraska-Wyoming. 


FlG    I53._siphon  Crossing  under    Rawhide  Creek,  Interstate  Canal,  Nebraska- 
Wyoming. 

from  the  canal  such  as  to  insure  against  injury  or  menace  to  the 
canal.  As  the  concrete  superpassage  will  have  a  much  smoother 
surface  than  the  channel  of  the  torrent,  its  effect  will  be  to 
accelerate  the  velocity  of  the  water,  and  it  may  be  advisable 


318  CANAL  STRUCTURES 

to  provide  a  protected  stilling  pool  or  other  means  of  checking 
its  velocity  to  avoid  destructive  erosion.  The  provision  of  a 
superpassage  applies  mainly  to  cases  where  the  torrent  to  be 
controlled  is  very  large,  and  no  loss  of  grade  in  the  canal  can  be 
permitted. 

Where  one  or  both  of  these  conditions  is  absent,  it 
may  be  preferable  to  carry  the  canal  under  the  torrent  in  a 
pressure  conduit  in  which  the  pressure  of  the  entering  water 
forces  the  water  to  the  same  elevation  at  the  issuing  end,  less 
certain  losses.  On  account  of  the  expense  of  a  such  a  conduit 
built  underground,  it  is  generally  necessary  to  make  it  of  much 
smaller  cross- section  than  the  canal  and  give  it  a  correspond- 
ingly greater  velocity.  This  consumes  head,  or  grade,  and 
hence  is  to  be  avoided  where  the  conservation  of  head  is  impor- 
tant, and  must  be  taken  into  consideration  when  comparing 
this  with  other  methods  of  handling  such  torrents.  The  canal 
should  be  lined  with  concrete  for  a  short  distance  above  the 
entrance  to  the  structure,  and  the  section  of  the  conduit  gradually 
warped  from  that  of  the  canal  to  that  of  the  pressure  tube,  so 
as  to  present  no  angles,  nor  sharp  turns  to  the  entering  water, 
that  would  create  eddies  or  otherwise  retard  its  velocity.  In 
this  way  the  head  consumed  in  entry  may  be  reduced  to  a 
minimum,  but  some  allowance  must  still  be  made  therefor, 
while  due  allowance  must  also  be  made  for  the  head  or  fall  in 
water  surface  necessary  to  produce  the  velocity  required  in  the 
pressure  conduit.  This  head  is  found  from  the  formula. 

72 

V  =  V  2£/z,  which  may  be  transformed  into  h  =  — . 

2£ 

In  this  case  V  =  the  difference  in  velocity  between  the  water 
flowing  in  the  canal  and  that  required  in  the  pressure  conduit. 
As  the  water  issues  from  the  conduit  into  the  canal  it  is  generally 
necessary  to  change  its  velocity  and  section  to  that  of  the  normal 
canal  section.  If  the  section  is  changed  by  warped  surfaces 
so  slowly,  gently  and  gradually  as  to  cause  no  waves  nor  eddies, 
it  is  possible  to  recover  nearly  all  the  velocity  head,  so  that  the 
main  losses  of  head  will  be  the  entry  head  and  the  friction  in 


CULVERTS 


319 


the  conduit.  When  the  approach  and  exit  are  properly  warped, 
and  the  inside  of  the  conduit  made  as  smooth  as  practicable, 
these  losses  of  head  are  all  small  except  when  the  conduit  is 
long,  or  its  velocity  very  high,  in  which  cases  the  friction  losses 
are  heavy. 

It  is  practicable  in  most  cases  to  secure  an  entry  coefficient 
between  80  and  90  per  cent,  by  proper  construction  of  the 
entrance,  and  to  recover  at  least  75  per  cent  of  the  velocity  head 
by  proper  construction  of  the  conduit  at  the  exit  upon  grade. 
To  secure  these  results,  the  bounding  surfaces  of  the  conduit 
must  be  very  gently  curved,  and  a  distance  at  entry  must  be 


Vertical  Rods  %"x  %'haeh  abutment       ] 
a_Rodajn  Cen.  WallL 


66  Longitudinal 


FIG.  154.  —  Reinforced  Concrete  Twin  Siphon,  Interstate  Canal,  Nebraska- 

Wyoming. 

consumed  in  the  transition  equal  to  twice  the  difference  between 
the  greatest  dimension  of  the  original  water  prism,  and  the 
corresponding  dimension  of  the  pressure  conduit.  The  issuing 
conduit  must  consume  in  transformation  about  double  the 
distance  required  for  the  entrance  by  the  above  rule. 

The  junction  of  the  structure  at  both  ends  must  be  safe- 
guarded by  curtain  and  wingwalls,  and  the  usual  precautions 
taken  to  prevent  percolation  around  them. 

The  pressure  conduit  must  be  built  well  below  the  grade  of 
the  torrent  it  crosses,  in  order  to  avoid  the  danger  of  a  washout. 

Where  a  flume  or  a  pipe  is  required  on  a  canal  line,  it  is 


320 


CANAL  STRUCTURES 


advisable  to  give  some  increased  grade,  in  order  to  induce  an 
increased  velocity  and  to  force  the  required  quantity  of  water 
through,  without  building  a  structure  as  large  as  would  be 


required  with  a  low  velocity.  The  quantity  of  water  carried  is 
expressed  by  the  equation,  Q  =  Av,  where  A  is  the  area  of  cross- 
section  of  the  conduit,  and  v  is  the  mean  velocity  of  the  flow- 
ing water.  Hence,  the  greater  the  velocity,  the  less  may  be 
the  area  of  cross-section,  and  as  a  flume  or  pipe  will  admit  of 


CULVERTS 


321 


322 


CANAL  STRUCTURES 


PIPES  323 

high  velocities  without  injury  much  expense  may  often  be  .saved 
by  increasing  the  grade,  and  velocity,  at  the  entrance  of  such 
a  structure.  The  high  velocity  is  also  desirable  to  prevent  the 
deposit  of  sand  or  gravel  in  a  pipe. 

12.  Pipes. — The  use  of  pipe  for  conveying  and  distributing 
water  for  domestic  use  is  nearly  universal,  and  it  has  the  impor- 
tant virtues  of  cleanliness,  convenience  and  economy  of  water. 
The  great  expense  involved  generally  prohibits  its  use  for  the 
large  volumes  of  water  handled  in  irrigation,  except  in  Southern 
California  and  such  localities  where  water  has  a  very  great 
value,  and  in  special  cases  where  pipe  may  be  used  as  inverted 
siphons  to  carry  water  across  depressions  under  pressure,  or 
around  steep  hillsides  where  canals  cannot  be  built.  Short 
pipes  are  also  used  as  culverts  to  carry  drainage  waters  under 
roads,  railroads  or  canals. 

The  material  of  construction  may  be  cast  iron,  sheet  steel 
or  iron,  wood,  reinforced  concrete,  vitrified  clay,  or  cement. 
When  properly  constructed,  reinforced  concrete  is  the  most 
permanent,  and  has  been  successfully  used  by  the  Reclamation 
Service  for  heads  as  high  as  no  feet.  For  heads  much  greater 
than  this,  steel,  cast  iron  or  wood  may  be  used.  For  heads  below 
20  feet  clay  tile  or  cement  is  sometimes  employed  without  rein- 
forcement. 

Wood  pipe  is  the  most  widely  used  pipe  for  irrigation,  but 
the  use  of  concrete  is  increasing,  as  it  becomes  better  known 
and  the  cost  of  wood  increases.  Wood  decays  rapidly  unless 
kept  saturated  with  water,  and  its  decay  is  much  hastened  by 
contact  with  earth,  unless  the  saturation  with  water  is  thorough 
and  continuous.  Confinement  of  water  under  high  pressure 
is  the  best  means  of  keeping  it  saturated,  and  hence  wood  pipe 
should  be  used  only  under  high  pressure,  unless  it  is  laid  under 
water  or  in  ground  perpetually  saturated.  Where  pipe  is 
exposed  to  the  air,  or  to  dry  earth  it  may  require  a  pressure  of 
50  feet  head  or  more  to  force  the  water  through  the  pores  of  the 
wood  fast  enough  to  supply  the  evaporation  from  the  surface. 
The  head  required  is  of  course  much  greater  in  an  arid  than  in  a 
humid  region  with  less  evaporation.  Where  the  head  is  less 


324  CANAL  STRUCTURES 

than  100  feet,  especially  in  arid  regions,  the  pipe  should  be 
protected  from  contact  with  earth,  and  its  life  may  be  greatly 
prolonged  by  keeping  it  well  painted  outside.  A  good  practice 
is  to  build  a  pressure  pipe  of  wood  for  the  distance  where  its 
pressure  head  exceeds  50  feet,  and  build  the  ends  of  reinforced 
concrete  where  the  pressure  is  less.  The  pipe  should  be  left 
full  of  water  during  the  non-irrigation  season,  and  any  con- 
siderable loss  from  leakage  should  be  replenished.  Redwood 
is  the  most  durable  wood  for  this  use,  but  cedar  and  Douglas  fir 
are  good  and  many  varieties  of  pine  have  been  used. 

Wooden  pipe  was  formerly  manufactured  by  boring  the 
center  out  of  logs,  and  such  pipe  is  reported  to  have  had  a 
durability  of  over  200  years  in  England,  and  over  100  years  in 
Philadelphia,  under  conditions  where  it  was  continuously 
saturated  with  water.  .  The  bored  log  is  very  wasteful  of 
material,  and  has  been  superseded  by  two  modern  types,  both 
widely  used  in  irrigation  work,  namely  the  continuous  stav^e 
pipe,  and  the  wire-wound  pipe. 

Continuous  stave  pipe  is  built  in  place  of  staves  carefully 
milled  from  selected  lumber,  to  have  concentric  circular  surfaces 
and  radial  edges.  The  ends  of  the  staves  are  arranged  to 
break  joints,  and  are  joined  by  metal  plates  inserted  in  sawkerfs 
in  both  staves,  and  slightly  wider  than  the  stave.  The  staves 
are  held  in  place  by  steel  bands,  the  ends  of  which  are  lapped  in 
a  cast-iron  shoe,  and  one  is  fitted  with  a  screw  nut  which  is  used 
to  tighten  the  band.  Specifications  found  in  Chapter  XXII 
of  this  book  give  in  detail  the  best  modern  practice. 

Wire-wound  wooden  pipe  is  made  in  joints  of  convenient 
length,  by  placing  the  staves  in  the  position  desired,  and  binding 
them  firmly  in  that  position  by  winding  heavy  wire  around  them 
in  spiral  form.  The  lengths  manufactured  vary  from  20  feet 
for  small  diameters,  to  8  feet  for  the  largest.  The  pipes  are 
usually  from  4  inches  to  24  inches  in  diameter,  though  larger  and 
smaller  sizes  are  sometimes  used.  Larger  sizes  than  36  inches 
can  best  be  made  on  the  ground,  of  the  continuous  stave 
type. 

Where  water  freezes  in  the  pipe  during  winter  it  should  be 


PIPES  325 

carefully  examined  for  leakage  before  the  opening  of  the  'irriga- 
tion season,  and  repaired  if  necessary. 

There  is  little  economy  in  using  wooden  pipe  for  pressures 
exceeding  200  feet,  as  above  that  head  the  necessary  steel  in 
the  bands  is  nearly  sufficient  for  heavy  steel  pipe,  which  is  thus 
much  cheaper.  Wood  pipe,  has,  however,  been  used  for  heads 
up  to  400  feet,  where  the  short  length  of  such  head  did  not 
justify  a  change  in  design. 

Reinforced  concrete  pipe  may  be  manufactured  in  place 
by  means  of  portable  forms,  and  good  results  have  been  obtained 
in  this  way.  It  is  necessary  to  keep  the  work  going  continu- 
ously, or  nearly  so,  as  concrete  does  not  bond  well  with  other 
concrete  that  has  been  cured.  The  difficulty  of  entirely  accom- 
plishing perfect  continuity,  and  of  obtaining  thoroughly  first- 
class  work  under  the  handicaps  of  field  conditions,  led  to  the 
introduction  of  another  method,  by  which  the  pipe  is  constructed 
in  sections  of  about  8  feet,  in  a  yard  where  ideal  conditions  can 
be  approximated  and  the  concrete  can  be  made  particularly 
dense  and  ideally  cured.  After  thorough  seasoning,  these  are 
hauled  to  the  field,  and  placed  during  weather  as  cold  as  permis- 
isble  without  freezing  the  mortar  used  in  forming  the  joints.  A 
movable  collar  form  is  placed  at  each  joint,  and  a  rich  cement 
mortar  is  poured  in  at  the  top  and  thoroughly  rammed. 

As  soon  as  the  forms  are  removed,  the  joints  are  covered 
with  wet  burlap  and  kept  moist  continuously  for  several  days. 
By  placing  the  pipe  in  cold  weather  while  it  is  contracted  by 
cold,  any  rise  of  temperature  places  it  in  compression  and 
tends  to  prevent  cracks.  It  should  be  backfilled  as  soon  as 
possible  after  seasoning  the  joints.  Pipe  46  inches  in  diameter, 
made  and  laid  in  this  manner  near  Hermiston,  Oregon,  has 
withstood  a  pressure  of  no  feet  for  several  years  without  notable 
leakage  or  any  repair. 

Steel  pipe  is  often  used  for  heads  exceeding  60  feet,  but  is 
seldom  economical  for  a  less  head.  It  Is  commonly  formed  by 
curving  a  sheet  of  steel  till  the  edges  lap,  and  riveting  them  in 
that  position.  If  considerable  head  must  be  withstood  it  is 
greatly  strengthened  by  having  two  rows  of  rivets,  parallel. 


326  CANAL  STRUCTURES 

Another  and  more  efficient  method  of  riveting  is  to  wind  the 
steel  in  a  spiral  and  fasten  the  spiral  lap  seam  by  a  single 
row  of  rivets.  The  transverse  seam  is  formed  by  forcing  the 
end  of  one  joint  into  another  far  enough  to  rivet,  or  if  the  pipe 
is  especially  heavy,  making  a  butt  joint  with  an  exterior  sleeve 
riveted  to  each  pipe.  The  life  of  the  pipe  is  greatly  increased  by 
keeping  it  well  coated  with  paint  or  tar. 

The  smaller  sizes  of  steel  pipe  are  formed  by  welding  the 
longitudinal  seams  instead  of  riveting,  and  are  joined  by  screwing 
the  ends  into  exterior  sleeves  made  to  fit. 

Lock-bar  pipe  has  the  longitudinal  joint  formed  by  upsetting 
the  edges  of  the  plate,  and  inserting  them  in  grooves  of  a  bar 
which  are  then  closed  by  hydraulic  pressure.  This  makes  a  joint 
equal  to  the  strength  of  the  plate  if  the  workmanship  is  good, 
and  avoids  the  interior  roughness  caused  by  rivets. 

The  use  of  small  pipe  in  distributing  irrigation  water  is 
rapidly  growing  as  water  becomes  more  valuable,  and  the  means 
of  the  irrigators  grow.  Where  this  is  simply  a  substitution  for 
open  ditches  it  is  customary  to  employ  cement  pipe,  which  can 
be  manufactured  in  place  by  machines  used  for  the  purpose. 
Cement  pipe  without  reinforcement  is  often  used  to  cross  undula- 
tions involving  pressures  up  to  15  feet,  and  hao  been  used  for 
20-foot  pressures.  In  these  cases,  however,  it  must  be  built 
with  especial  care,  and  heads  above  10  feet  should  be  avoided 
when  practicable,  or  a  light  reinforcement  in  the  form  of  a  spiral 
steel  wire  may  be  used.  The  use  of  cement  pipe  as  of  cement- 
lined  ditches  is  growing  and  is  to  be  commended  and  encouraged. 

There  are  many  formulae  for  computing  the  discharge  capac- 
ity of  pipes,  all  based  more  or  less  on  experiment,  seventeen  of 
which  are  given  in  the  Engineering  Record,  Vol.  LXVIII,  p.  667. 
The  most  noted  of  these  perhaps  are  those  of  Bazin,  D'Arcy, 
Kutter  and  Weisbach,  which  all  differ  considerably  in  results. 
A  careful  study  of  these,  and  the  reasoning  on  which  they  are 
based,  leads  to  the  conclusion  that  great  refinement  of  com- 
putation is  useless,  and  that  we  can  hardly  hope  with  present 
knowledge  to  predict  much  nearer  than  8  or  10  per  cent,  the 
capacity  of  any  pipe  in  advance  of  its  construction,  and  that 


PIPES 


327 


p« 


328 


CANAL  STRUCTURES 


PIPES 


329 


L 


FIG.  1 60. — Removing  Inside  Steel  Forms  from  Concrete  Pressure  Pipe,  Boise 

Project. 


FIG.   161. — Manhole  and  Concrete  Collars  on  Concrete  Pressure  Pipe.  Boise 

Project. 


330  CANAL  STRUCTURES 

such  a  margin  of  safety  should  usually  be  provided  where  the 
capacity  is  important. 

The  U.  S.  Reclamation  Service  has  adopted  the  following 
formulae  for  the  capacity  of  pipes  used  in  irrigation  and  drainage : 

Wood-stave  pipe Q  =  1.35  D27  H555 

Cast-iron  pipe <2  =  i-3i  D27  H555 

Concrete  pipe Q  =  1.24  D27  H555 

Riveted  steel Q  =  1.18  D27  H555 

Drain  tile Q=  D27  H555 

where  Q  =  Discharge  in  cubic  feet  per  second ; 
D  =  Diameter  of  pipe  in  feet ; 
H  =  Available  head  in  feet  per  1000. 

13.  Tunnels. —Where  the  canal  location  must  leave  the 
contour  grade  line  in  order  to  avoid  a  long  detour  around  a 
ridge  or  hill,  or  to  escape  a  hazardous  location  on  its  steep  slopes, 
it  may  pass  through  the  hill  in  a  deep  cut,  or  if  this  is  too  deep, 
may  tunnel  through.  Whether  a  cut  or  tunnel  is  to  be  preferred 
depends  mainly  upon  the  depth  of  cut  and  the  character  of 
material,  and  is  chiefly  a  question  of  cost.  Other  conditions 
being  equal,  a  tunnel  is  to  be  preferred,  as  it  will  generally  give 
less  trouble  and  expense  in  maintenance.  There  is  frequently 
presented  also  the  alternative  of  going  around  on  a  grade  line 
in  a  flume  or  canal,  or  a  combination  of  both.  The  cost  must 
be  largely  in  favor  of  the  latter  to  justify  its  construction,  as 
side-hill  canals  and  flumes  are  expensive  to  maintain,  and  may 
be  very  hazardous.  This  depends  largely  on  the  material, 
and  is  not  easv  to  estimate  in  advance.  Cases  are  not  rare 
where  a  canal  located  around  a  hill  gave  so  much  trouble  by 
seepage  and  developing  slides  that  it  was  later  abandoned  for  a 
safer  location  in  tunnel. 

In  a  majority  of  cases  tunnels  require  lining  to  prevent 
caving  or  swelling  of  the  material  in  which  they  are  built,  and 
in  many  instances  where  this  is  not  the  case  lining  may  be 
advisable  to  present  smoother  surfaces  to  the  flowing  water, 
reduce  the  friction  and  thus  increase  the  capacity.  This  is 


TUNNELS  331 

generally  the  case  where  grade  is  valuable,  but  where  there  is  a 
surplus  of  grade  and  the  rock  is  hard  and  firm,  the  lining  may  be 
omitted  from  a  tunnel  of  moderate  size.  A  small  tunnel  with 
good  smooth  concrete  lining  will  discharge  nearly  twice  as  much 
water  as  one  with  rough  rock  interior  of  the  same  dimensions 
and  grade.  A  lining  may  in  some  cases  be  required  to  prevent 
loss  of  water  through  crevices  in  the  rock,  but  such  conditions 
are  infrequent  in  material  firm  enough  to  stand  without  lining. 

The  smallest  tunnel  in  which  it  is  economical  to  carry  on 
heavy  work  is  about  4  feet  wide  and  6  feet  high,  and  there  is 
little  or  no  economy  in  making  a  tunnel  smaller  than  this.  It 
is  best  to  leave  about  a  foot  of  vacant  air  space  above  the  water 
in  any  tunnel,  to  prevent  waves  or  any  chance  obstruction  from 
causing  the  water  to  touch  the  top  of  the  tunnel,  and  thus  causing 
it  to  "  seal,"  that  is  to  fill  to  the  top,  and  thus  increase  the  friction 
which  would  reduce  the  velocity  and  resulting  discharge. 

It  is  generally  advisable  to  construct  the  top  of  a  tunnel 
in  the  form  of  an  arch.  This  shape  has  a  tendency  to  resist 
caving  of  the  top  and  gives  the  maximum  holding  power  to  any 
lining  that  may  be  provided.  It  also  provides  an  air  space  that 
is  effectual  against  sealing  without  sacrificing  much  cross-section 
for  this  purpose.  The  sides  of  the  tunnel  are  generally  straight 
vertical  lines,  and  the  bottom  a  straight  horizontal  line,  or  a 
slight  curve  concave  upward.  It  is  generally  considered  cheapest 
to  make  such  simple  lines,  especially  in  case  lining  is  required, 
for  which  forms  must  be  provided.  This  advantage,  however, 
is  not  great,  and  wherever  the  ground  to  be  tunneled  is  insecure, 
greater  resistance  to  caving  may  be  secured  by  giving  the  per- 
imeter of  the  tunnel  a  curved  form,  so  as  to  present  arch  action 
in  every  direction  against  outside  pressure.  For  this  purpose 
a  circular  section  is  sometimes  provided,  but  .this  is  incon- 
venient of  construction  and  not  entirely  logical  for  its  purpose. 
The  first  tendency  of  caving  ground  is  downward  in  obedience 
to  gravity,  and  where  this  is  resisted,  and  the  mobility  consider- 
able, a  secondary  tendency  is  in  a  horizontal  direction.  It  is 
therefore  logical  to  build  the  top  of  the  tunnel  on  a  curve  of 
shorter  radius  than  that  of  the  sides  or  bottom,  but  to  curve 


332  CANAL  STRUCTURES 

these  also,  if  outside  pressures  are  to  be  expected.  A  logical 
and  convenient  shape  conforming  to  these  principles,  has  become 
standard,  and  is  as  follows:  The  top  of  the  tunnel  is  a  half 
circle,  drawn  to  such  radius  as  the  desired  capacity  requires, 
which  may  be  indicated  by  the  symbol  R.  From  each  end  of 
the  horizontal  diameter,  with  a  radius  2R,  an  arc  is  described 
connecting  with  the  half  circle  and  continuing  its  lines  downward. 
From  highest  point,  or  apex  of  the  circular  top  as  a  center,  with 
a  radius  2R,  an  arc  is  described  to  form  the  bottom  or  invert 
of  the  tunnel,  intersecting  the  sides.  This  shape  is  shown  in 
Fig.  250,  and  is  sometimes  called  a  "  horseshoe  "  section,  for 
obvious  reasons. 

Clay  and  shale  and  some  other  materials  have  a  tendency 
to  swell  when  exposed  to  atmospheric  influences  and  may  con- 
tinue the  swelling  process  long  after  lining  has  been  placed. 
Where  such  tendency  exists,  it  is  important  to  employ  a  curved 
section  of  lining  in  order,  by  arch  action,  to  resist  the  thrust 
of  the  "  swelling  ground." 

Where  it  is  desirable  to  Duild  the  tunnel  of  the  smallest 
economical  size,  the  invert  may  be  drawn  to  a  radius  of  3^ 
instead  of  2R,  and  by  giving  the  R  a  value  of  2  feet,  we  obtain 
an  extreme  height  of  6  feet  and  an  extreme  width  of  4  feet, 
which  is  about  the  minimum  desired.  The  standard  section, 
however,  Fig.  249,  produces  a  greater  hydraulic  radius,  and 
hence  involves  less  friction  losses,  and  wherever  it  gives  a  total 
height  of  6  feet  or  more,  is  more  convenient  and  hence  more 
economical  in  construction  and  operation. 

The  equipment  and  operations  for  tunnel  construction  vary 
widely.  They  depend  chiefly  upon  the  character  of  material 
and  the  length  of  the  tunnel. 

Tunnel  work  at  best  is  quite  slow.  The  room  for  work  is  so 
restricted  that  only  a  few  men  can  engage  upon  it  at  one  time, 
and  if  the  tunnel  is  very  long  it  generally  is  the  feature  that 
determines  the  necessary  time  consumed  in  the  construction. 
The  utmost  speed  therefore  becomes  important  and  it  is  cus- 
tomary to  work  night  and  day  upon  both  headings. 

If  any  central  portion  of  the  tunnel  is  near  enough  the  surface 


TUNNELS  333 

to  be  reached  from  a  shaft  of  moderate  depth,  this  may  be  made 
a  means  of  expediting  its  completion  by  affording  other  points 
of  attack.  Sometimes  it  may  be  entered  at  the  side  from  a 
canyon  nearby  through  a  branch  tunnel  called  an  adit.  In 
deciding  upon  the  location  of  the  tunnel  it  is  not  uncommon  to 
deviate  from  a  straight  line  sufficiently  to  permit  the  use  of  an 
adit  to  cheapen  construction  and  expedite  completion. 

The  length  of  a  tunnel  not  only  increases  the  time  of  con- 
struction but  greatly  increases  the  unit  cost.  It  determines  the 
distance  through  which  men  must  travel  to  and  from  their 
work  and  through  which  all  the  excavated  material  must  be 
transported  and  all  of  the  materials  for  timbering  and  lining  the 
tunnel  must  also  be  taken,  together  with  gpwder  and  other 
materials  for  construction. 

A  long  tunnel  must  also  be  provided  with  ventilation.  The 
gases  generated  by  explosives  are  unfit  for  breathing  and  may 
be  very  injurious  or  fatal  if  taken  into  the  lungs  in  considerable 
quantities.  It  is  therefore  necessary  to  provide  ventilation 
by  some  means.  With  a  short  tunnel  it  may  be  feasible  to 
work  only  alternate  shifts  or  to  provide  such  intervals  between 
shifts  that  the  gases  will  dissipate  themselves  so  that  artificial 
ventilation  may  not  be  necessary.  As  the  work  advances 
farther  and  farther  from  the  entrance,  artificial  ventilation 
becomes  more  and  more  necessary,  especially  if  speed  require- 
ments are  such  as  to  prevent  the  suspension  of  work  for  con- 
siderable intervals.  Necessary  ventilation  is  generally  provided 
by  running  light  sheet-iron  pipe  from  the  portal  or  from  a  shaft 
and  with  a  blower  either  pumping  air  from  the  heading  or 
forcing  fresh  air  in  to  displace  it.  Usually  the  suction  process 
is  used  immediately  after  the  blast  to  bring  out  the  concentrated 
gases.  When  these  are  fairly  well  disposed  of  the  current  is 
reversed  and  fresh  air  blown  in  next  the  heading.  In  this  way 
only  a  few  minutes  need  be  lost  from  the  work  after  a  blast 
and  by  setting  the  blast  off  just  before  meal  time  the  atmosphere 
is  satisfactory  for  the  resumption  of  work  immediately  after 
the  meal  is  finished. 

There  is  a  large  variation  in  the  speed  that  can  be  achieved 


334 


CANAL  STRUCTURES 


in  constructing  a  tunnel,  even  where  the  best  facilities  are 
provided.  Where  the  material  is  of  shale  or  of  indurated  sand  or 
similar  substances  which  are  sufficiently  coherent  to  stand 
temporarily  without  much  timbering  and  yet  are  soft  enough 
to  be  cut  rapidly  with  power  augers  and  do  not  require  the  slow 
process  of  drilling,  the  work  can  proceed  rapidly  and  20  or  25 
feet  of  progress  may  be  made  in  one  day  on  a  single  heading. 
Where  the  rock  is  hard,  requiring  much  drilling,  the  process  is 
necessarily  slow  .and  may  be  only  a  tenth  of  what  it  would  be 
under  the  most  favorable  circumstances. 


TABLE  XXXII.— TUNNELS 


Project 

Tunnel 

Capacity, 
Sec.  ft. 

Length, 
Feet 

Cost 
Excl.  G.  E. 

Cost  per 
Foot 

Grand  Valley 

No   i 

I42s 

7,723 

$265,200 

$71 

Grand  Valley  .... 

No.  2  

1425 

1,655 

117,400 

71 

Grand  Valley  

No.  3  

670 

7,292 

334,ioo 

46 

Uncompahgre  .... 

Gunnison  

IOOO 

30,645 

3,100,000 

101 

Sun  River  

Pishkun  No.  i  

IOOO 

695 

54,100 

78 

Sun  River  

Pishkun  No.  2  

IOOO 

1,022 

80.900 

79 

Sun  River  

Pishkun  No.  3  

IOOO 

2,277 

142,700 

63 

Klamath 

Main  Canal. 

I2OO 

3,^OO 

190,700 

58 

Belle  Fourche.  .  .  . 

S.  Canal  

35° 

I,3O6 

33,200 

25 

Strawberry  

Strawberry  

600 

19,897 

1,076,000 

54 

Strawberry  

Power  Canal  No.  i  .  . 

500 

800 

27,600 

34 

Strawberry  

Power  Canal  No.  2.  . 

500 

705 

21,800 

3i 

Okanogan 

Conconully  Outlet 

ooo 

39C 

12  800 

32 

Yakima  (Tieton)  . 

6  tunnels  

300-350 

11,863 

397,100 

33 

Shoshone  

Corbett  

IOOO 

17,355 

1,133,000 

65 

The  most  difficult  tunnel  work,  however,  is  where  the  material 
to  be  penetrated  is  running  sand  which  requires  close  tight 
timbering  to  prevent  enormous  caves  and  filling  of  the  tunnel 
with  loose  sand.  Various  means  of  solidifying  this  have  been 
suggested,  but  without  much  success  so  far.  One  method  is  to 
inject  water  into  the  sand  ahead  of  the  work,  which  makes  it 
more  coherent  and  affords  time  for  placing  timber  after  excava- 
tion. Another  suggestion  is  to  inject  cement  grout  for  the  same 
purpose.  These  processes  present  difficulty  in  securing  an  even 


HIGHWAY  CROSSINGS  335 

distribution  of  the  injected  material,  but  where  this  can  be 
accomplished  they  help  materially  in  holding  the  refractory 
sand. 

The  above  table  of  tunnels  constructed  by  the  Reclama- 
tion Service,  shows  the  entire  cost  excluding  overhead,  general 
and  indirect  charges,  and  show  a  great  variety  of  unit  costs. 
The  highest  unit  cost,  that  of  the  Gunnison  Tunnel,  is  due  partly 
to  the  fact  that  it  is  the  longest  in  the  list,  but  still  more  to  the 
extremely  difficult  and  hazardous  conditions  there  encountered. 
These  included  great  deposits  of  mud  and  gravel  which  were 
difficult  to  hold,  large  quantities  of  water,  much  of  it  scalding 
hot,  and  numerous  difficulties  with  carbon  dioxide  and  explosive 
gases  imprisoned  in  the  rocks  and  liberated  by  the  tunnel  work. 
The  construction  was  frequently  shut  down  from  these  means; 
heavy  pumping,  elaborate  ventilation  and  equipment  were  re- 
quired, and  in  the  process  many  lives  were  lost. 

Tunneling  is  a  highly  developed  specialty,  requiring  for 
economical  and  efficient  prosecution  a  high  degree  of  skill  in 
the  use  of  explosives,  in  the  timbering  and  holding  of  refractory 
material,  and  in  organizing,  training,  and  operating  a  crew  to 
work  efficiently  under  cramped  and  disagreeable  circumstances. 

14.  Highway  Crossings. — In  general  it  is  necessary  to  provide 
highway  bridges  where  irrigation  canals  cross  public  highways 
in  use  at  the  time  the  canals  are  constructed.  These  should 
usually  have  abutments  of  concrete  or  steel  cylinders  filled  with 
concrete,  as  wood  will  rapidly  decay  in  contact  with  earth. 
The  superstructure  of  small  bridges  may  properly  be  built  of 
wood,  and  the  larger  bridges  requiring  trusses  may  have  all 
compression  members  of  wood  and  the  tension  members  of  steel. 
It  is  very  undesirable  to  permit  any  piers  in  the  water  prism 
of  the  canal,  as  they  cause  some  loss  of  head,  and  catch  drift- 
wood, weeds,  etc.,  and  increase  maintenance  cost  in  several 
ways. 

Where  it  is  necessary  to  cross  existing  railways,  the  railway 
company  is  sure  to  require  a  very  safe  structure,  and  there  is 
sometimes  a  tendency  to  carry  this  requirement  to  an  extreme. 
There  should  never  be  reluctance  to  provide  such  structures 


336 


CANAL  STRUCTURES 


m 


FIG.  162. — High  Line  Canal,  Spanish  Fork  Valley,  Utah,  Covered  to  Protect 
against  Land  and  Snow  Slides. 


FIG.  163. — Headgates,  Sluice  Gates,  and  Sand  Basins,  High  Line  Canal,  Spanish 

Fork  Valley,  Utah. 


SAND   TRAPS  337 

with  ample  margin  of  safety,  as  a  failure  might  lead  to  the  wreck 
of  a  railway  train,  an  accident  usually  far  more  serious  than 
a  canal  break.  Crossings  of  railways  established  after  the  canal 
is  built  should  be  at  the  expense  of  the  railway,  and  should  be 
of  the  same  character  and  margin  of  safety  as  those  built  at  the 
expense  of  the  canal  authorities.  The  same  rules  apply  to 
highway  crossings  required  after  the  construction  of  the 
canal. 

Where  the  grade  of  the  railway  or  highway  is  several  feet 
above  the  surface  of  the  canal  water,  and  the  canal  is  not  too 
large,  it  is  best  to  carry  the  road  across  on  a  fill  over  a  culvert 
provided  for  the  canal  water.  This  avoids  interference  with  the 
road  in  any  way,  and  the  earth  distributes  the  pressure  upon  the 
culvert.  Where  the  grade  of  the  canal  is  about  the  same  as  that 
of  the  railroad,  it  is  seldom  that  the  latter  is  willing  to  change  its 
grade,  and  it  becomes  necessary  to  introduce  a  pressure  conduit 
to  carry  the  canal  under  the  railway.  The  chief  objection  to 
this  is  the  tendency  to  collect  sand  and  silt  in  the  conduit  under 
the  railways.  Where  possible  the  conduit  should  be  given  a 
velocity  sufficient  to  carry  through  any  material  the  canal 
can  bring  in.  For  this  purpose,  velocities  of  3  feet  per  second 
for  silt,  4  feet  for  sand,  and  5  feet  for  fine  gravel  will  prevent 
deposit,  but  higher  velocities  may  be  required  to  pick  up  and  carry 
out  material  previously  deposited.  Where  it  is  not  feasible  to 
provide  increased  velocities,  it  may  be  necessary  to  provide 
that  the  lowest  point  of  the  conduit  be  at  one  side  of  the  railway, 
where  it  may  be  cleaned  out  through  a  manhole.  This  is  seldom 
necessary  unless  the  canal  is  heavily  silt  bearing. 

15.  Sand  Traps. — The  frequent  presence  of  sand  in  canals 
where  it  is  often  a  serious  nuisance,  requires  the  employment  of 
devices  by  which  it  may  be  removed  and  these  are  variously 
called,  sand  traps,  sand  boxes,  sand  gates,  and  sluicing  devices. 
On  p.  250  reference  occurs  to  devices  for  preventing  or  minimizing 
the  entrance  of  sand  into  a  canal  from  the  river.  These  are  not 
always  possible,  and  where  provided  are  seldom  completely 
effective,  and  hence,  where  water  is  taken  from  a  sandy  stream, 
it  is  usually  necessary  to  employ  some  means  to  get  rid  of  the 


338 


CANAL  STRUCTURES 


sand  entering  the  canal.     In  addition  to  this,  the  canal  may 

receive  sand  from  side  drainage  taken  into  the  canal. 

The  objections  to  sand  in  the  canal  are  several: 

i.It.  tends  to  deposit  in  siphons  near  the  inner  bank  on 

curves,  and  at  other  points  where  the  velocity  is  checked  or 

eddies  occur,  and  to  form  bars  which  reduce  the  capacity  of  the 

canal,  and  cause  much  annoyance  and  expense  in  their  removal. 

2.  Sand  occurring  in  water  carried  through  siphons,  flumes, 

or  lined  channels  at  high  velocities,  has  a  tendency  to  wear  such 

channels,  or  other  structures  subject  to  the  abrasion  of  the  sand. 


FIG.  164. — Cross-section  of  Sand  Box,  Santa  Ana  Canal,  Cal. 

3.  Sand  occurring  in  water  to  be  used  for  power  causes  rapid 
wear  and  destruction  of  water  wheels. 

4.  Where  sand,  is   successfully   carried    through   the  canal 
system  to   the  farm,  which  is  difficult  to  accomplish,  it  soon 
fills  the  farm  distributaries,  and  as  it  contains  very  little  fertility 
it  is  a  nuisance  without  redeeming  benefits. 

5.  Sediments  of  all  kinds  and  sizes  carried  in  a  feed  canal  to 
a  reservoir  tend   to  fill   the   reservoir  and  destroy  its  storage 
capacity. 


SAND  TRAPS 


339 


The  first  four  of  these  objections  do  not  apply  in  the  .same 
degree  to  the  finer  sediment  in  the  form  of  silt  or  clay,  which 
have  less  tendency  to  deposit  and  clog  the  works,  and  contain 
a  much  larger  percentage  of  available  plant  food,  and  although 
these  finer  sediments  do  cause  some  annoyance  and  expense, 
they  are,  when  in  moderate  quantities,  much  to  be  desired  for 
their  fertilizing  value  when  deposited  in  the  field,  and  such 
sediments  deposited  in  moderate  quantities  in  the  canal  system, 
tend  to  seal  it  and  thus  to  reduce  seepage  losses,  especially 
where  the  canal  is  located  in  coarse  and  porous  materials.  A 
film  of  clay  over  the  perimeter  of  a  canal  also  tends  to  reduce 
friction  and  thus  increase  discharge. 


FIG.  165. — Sand  Box,  Leasburg  Canal,  Rio  Grande  Valley,  New  Mexico. 

Fortunately  the  coarser  particles,  which  are  so  objectionable, 
are  more  easily  separated  from  the  water  by  settlement,  and  it 
thus  becomes  practicable  to  eliminate  them  in  a  large  degree. 

The  measures  available  for  combating  the  sand  nuisance 
may  be  divided  into  two  classes,  one  of  which  is  essentially 
preventive  and  the  other  curative: 

1.  Processes  of  settling,  sluicing  and  skimming  the  water 
so  as  to  prevent  the  entrance  of  sand  into  the  canal.     These  are 
preventive  measures. 

2.  Processes  of  settling  the  sediments  in  basins  or  depressions 
in  the  canal  system,  and  sluicing  them  back  into  the  stream, 
or  into  other  drainage  lines. 

The  preventive  measures  are  described  in  the  article  on 
headworks  on  p.  248.  Various  devices  are  employed  to  rid 
the  canal  waters  of  sand. 


340 


CANAL  STRUCTURES 


In  the  vicinity  of  cross- 
drainage  or  of  the  parent 
stream  the  canal  may  be  given 
an  abnormally  large  section 
and  a  depressed  bottom,  and 
the  slow  velocity  corresponding 
to  the  enlarged  section  causes 
a  deposit  of  the  heavier  and 
coarser  solids,  which  are  depos- 
ited in  the  bottom  of  the  en- 
larged section.  A  gate  or  set 
of  gates  is  provided  with  its  sill 
at  the  bottom  of  the  depressed 
portion,  and  when  this  is  opened, 
the  increased  grade  induces  a 
high  velocity  over  the  deposited 
sediment,  and  the  rushing 
waters  carry  it  out  into  the 
drainage  line  utilized,  which  is 
flushed  by  its  natural  freshets. 

The  efficiency  of  this  method 
may  be  increased  by  providing 
a  false  bottom  to  the  canal  on  a 
level  with  its  normal  bed.  This 
false  bottom  may  be  formed 
of  triangular  bars  with  a  sharp 
edge  upward,  spaced  a  slight 
distance  apart,  so  that  sand  set- 
tling will  fall  through  between 
the  bars,  to  the  bottom  of  the 
depression.  The  space  below 
this  false  bottom,  should  be 
provided  with  curved  guide 
walls  or  grooves  to  guide  the 
water  to  the  sluice  gates. 

The  false  bottom  serves  to 
prevent  upward  currents  and 


SAND   TRAPS  341 

eddies  that  retard  settlement  of  the  sand,  and  the  curved  guide 
walls  accelerate  the  sluicing  velocity  of  the  water  and  facilitate 
the  movement  of  the  sand  under  its  influence.  The  channels 
between  the  guide  walls  may  be  each  provided  with  a  separate 
gate  so  that  they  may  be  separately  sluiced  if  desired.  The 
combined  capacity  of  all  the  gates  should  be  somewhat  greater 
than  the  capacity  of  the  canal,  in  order  to  achieve  maximum 
efficiency. 

Where  the  canal  waters  are  carried  across  a  stream  or  a  large 
ravine  in  a  flume,  this  may  be  provided  with  a  series  of  hoppers 
reaching  below  the  grade  of  the  flume,  in  which  the  sand  may 
settle,  and  a  valve  in  the  bottom  of  each  hopper  may  be  opened 
at  proper  intervals  to  let  the  sand  fail  out. 

Some  device  of  this  kind  is  generally  employed  just  above  a 
power  plant  fed  by  a  canal  from  a  sandy  stream.  It  is  also  wise 
to  provide  such  an  arrangement  for  desilting  above  a  pressure 
pipe  or  inverted  siphon  where  low  velocities  occurring  at  times 
when  the  canal  is  being  used  at  part  capacity  might  clog  the 
pipe  with  deposits  of  sand  if  not  prevented. 

Desilting  devices  are  in  successful  practical  operation  in 
numerous  localities,  and  their  efficiency  is  greatly  assisted  by 
the  fact  that  the  coarser  particles  of  sand  have  a  tendency  to 
travel  on  or  near  the  bottom  of  the  stream.  A  considerable 
proportion  of  the  coarsest  are  simply  rolled  along  the  bottom 
in  miniature  waves  or  dunes  of  sand,  and  are  easily  deposited 
in  traps  like  those  described. 

In  some  cases  settling  basins  are  arranged  in  duplicate,  side 
by  side,  so  that  while  one  is  in  use  the  other  may  be  cleaned,  and 
thus  by  alternating  the  closure  of  the  canal  is  avoided. 


CHAPTER  XV 
STORAGE  RESERVOIRS 

i.  Classes  of  Storage  Works. — Reservoirs  are  employed  to 
regulate  the  flow  of  water  in  such  manner  as  to  accommodate 
the  rate  of  use,  and  prevent  waste  when  the  supply  exceeds 
the  demand,  holding  it  for  use  at  the  time  the  requirements 
exceed  the  natural  supply. 

The  storage  of  water  for  ordinary  irrigation  purposes  requires 
favorable  topographic  conditions  to  make  it  financially  feasible. 
Such  conditions  must  make  possible  the  storage  of  a  large 
quantity  in  a  broad  capacious  basin,  wholly  or  partly  natural, 
where  the  dam  or  other  structures  necessary  to  complete  it 
are  of  moderate  dimensions  and  cost,  as  compared  with  the 
quantity  of  water  stored.  A  location  where  storage  can  be 
obtained  at  moderate  cost  is  called  a  reservoir  site,  and  such 
sites  may  be  classified  with  respect  to  their  topographic  features 
into  four  classes  as  follows: 

1.  Natural  lake  basins; 

2.  Those  located  on  natural  drainage  lines,  the  flow  of  which 
they  regulate; 

3.  Those  located  in  depressions  away  from  natural  streams, 
requiring  the  water  for  storage  to  be  conducted  to  them; 

4.  Artificial  reservoirs  located  in  places  having  no  special 
natural  adaptation  to  such  use. 

Natural  lakes  are  often,  in  their  natural  state  important 
regulators  of  drainage  waters  which  they  receive.  By  con- 
trolling the  outlet,  by  means  of  a  dam  and  regulating  gates,  a 
large  amount  of  storage  may  often  be  secured  very  cheaply; 
the  cheapest  storage  works  in  the  world  in  proportion  to  capac- 
ity, are  those  which  utilize  natural  lake  basins. 

342 


SELECTION  OF  A   RESERVOIR  SITE  343 

The  most  abundant  reservoir  sites  are  those  on  natural 
drainage  lines,  but  they  require  careful  precautions  to  safely 
discharge  the  flood  waters  of  the  stream,  and  are  often  quite 
expensive  in  proportion  to  capacity. 

Many  natural  depressions  in  plains  or  benches  partially 
enclosed  by  high  ground  can  be  converted  into  reservoirs  by 
banks  of  moderate  dimensions  to  close  the  gaps  between  the 
hills,  and  many  natural  "  dry  lakes  "  can  be  made  available 
by  cutting  outlets  to  draw  off  stored  waters.  Such  reservoirs 
must  have  their  water  supply  carried  to  them  by  canals  from 
natural  streams.  Some  reservoirs  are  constructed  on  small 
drainage  lines  on  account  of  favorable  topographic  conditions, 
and  receive  their  main  water  supply  through  feeders  from  larger 
streams  in  the  neighborhood. 

Natural  depressions,  forming  dry  or  intermittent  lakes,  are 
sometimes  caused  by  the  collapse  of  subterranean  caverns 
caused  by  the  solvent  and  erosive  action  of  subterranean  waters, 
or  otherwise.  Depressions  thus  formed  are  unsuitable  for 
reservoirs  on  account  of  the  easy  escape  of  the  waters  through 
the  subterranean  passages  in  their  vicinity.  Dry  lakes  should 
be  carefully  examined  for  the  existence  of  those  conditions, 
before  being  adopted  as  reservoir  sites. 

Artificial  reservoirs  are  sometimes  constructed  by  excavating 
basins  and  using  the  material  in  the  formation  of  banks  to  confine 
the  water.  Such  reservoirs  are  very  expensive  per  unit  of 
storage  capacity,  and  can  be  used  only  in  cases  where  water  has  a 
high  value,  as  for  domestic  purposes  or  the  irrigation  of  gardens. 

Shallow  reservoirs  are  usually  to  be  avoided,  as  the  losses 
from  them  by  evaporation  and  percolation  are  relatively  large, 
and  where  they  are  shallow  enough  to  permit  the  sunlight  to 
penetrate  to  the  bottom,  they  are  likely  to  be  infested  by  aquatic 
vegetation.  To  prevent  the  growth  of  this,  shallow  reservoirs 
for  city  supplies  should  be  covered  to  exclude  the  sunlight. 

2.  Selection  of  a  Reservoir  Site. — Among  the  more  important 
considerations  affecting  tke  feasibility  and  value  of  a  reservoir 
site  are: 

i.  Its  relation  to  the  irrigable  lands. 


344  STORAGE  RESERVOIRS 

2.  Its  relation  to  the  water  supply. 

3.  The  topography  of  the  site. 

4.  The  geology  of  the  site. 

A  careful  examination  should  be  made  of  the  region  where 
storage  is  desired,  to  discover  all  possible  reservoir  sites  and 
compare  their  value  and  cost  in  order  that  the  most  favorable 
may  be  selected.  This  requires  a  practiced  eye  and  trained 
judgment  capable  of  selecting  the  most  advantageous  locations 
for  survey,  otherwise  much  time  and  money  may  be  wasted  on 
the  survey  of  indifferent  locations. 

The  reservoir  must  lie  at  a  sufficient  altitude  above  the 
irrigable  lands  to  permit  the  delivery  of  water  to  them  by  gravity 
flow,  or  in  special  cases  by  pumping  to  moderate  heights,  and 
should  be  as  near  as  possible  to  those  lands  so  that  the  losses  in 
transportation  may  be  small.  The  site  must  be  at  such  a  point 
as  to  intercept  a  sufficient  water  supply,  or  so  that  such  a  supply 
can  be  conducted  to  it.  Where  the  reservoir  is  on  a  stream, 
it  often  happens  that  it  is  such  a  distance  above  the  lands  to  be 
irrigated  that  when  the  water  is  needed  it  is  released  from  the 
reservoir  and  allowed  to  flow  down  the  stream  bed  for  some 
distance,  until  it  reaches  the  point  where  it  is  necessary  to 
divert  it  to  reach  the  lands  for  which  it  is  intended.  If  this 
distance  is  long,  consideration  must  be  given  to  the  losses  in 
transit  to  be  expected.  Due  regard  must  also  be  had  to  the 
drainage  intercepted  by  each  possible  site,  and  the  bearing  of  this 
element  on  the  water  supply. 

It  is  always  desirable  to  locate  the  reservoir  as  near  as  pos- 
sible to  the  irrigable  lands,  as  otherwise,  the  long  time  required 
in  transit  from  the  reservoir  to  the  lands  makes  it  difficult  to 
regulate  the  water  supply  according  to  the  fluctuating  needs  of 
irrigation,  and  much  water  must  be  wasted  most  of  the  time 
in  order  to  insure  a  full  supply  when  needed. 

3.  Geology  of  Reservoir  Sites. — Having  ascertained  the 
desirability  of  the  reservoir  site  topographically  and  hydro- 
graphically,  the  geology  should  be  carefully  studied,  to  ascertain 
the  character  and  dip  of  the  strata  underlying  the  proposed 
reservoir.  The  geological  conformation  may  be  such  as  to 


GEOLOGY  OF  RESERVOIR  SITES  345 

contribute  to  the  efficiency  of  the  reservoir,  or  it  may  prove  so 
unfavorable  as  to  be  irremediable  by  engineering  skill.  A 
reservoir  site  which  is  situated  in  a  synclinal  valley  is  gener- 
ally favorable.  In  this  the  strata  incline  from  the  hills  towards 
the  lower  lines  of  the  valley,  and  water  which  may  fall  on  to 
these  hills  will  find  its  way  by  percolation  into  the  reservoir, 
thus  adding  to  its  volume.  An  anticlinal  valley  is  much  less 
favorable  for  a  reservoir  site.  In  such  a  valley  as  this  the  strata 
dip  away  from  the  reservoir  site  and  may  permit  of  the  escape 
of  much  of  the  impounded  water.  A  class  of  geological  forma- 
tion intermediate  between  these  two  is  that  in  which  the  valley 
has  been  eroded  in  the  side  of  strata  which  dip  in  one 
direction.  Here  the  upper  strata  tend  to  lead  water  from 
the  adjoining  hills  into  the  reservoir,  while  the  strata  on 
the  lower  side  tend  to  carry  it  off  from  the  reservoir.  If 
the  surface  of  the  proposed  reservoir  site  is  composed  of 
a  deep  bed  of  coarse  sand  or  gravel  the  percolation  through 
this  may  be  so  great  as  to  seriously  impair  the  efficiency  of 
the  reservoir. 

The  most  careful  scrutiny  should  be  given  to  reservoir  sites 
in  regions  of  extensive  lava  flows,  as  such  formations  often 
contain  hidden  crevices  and  caverns  through  which  the  water 
may  escape  from  the  reservoir.  Oregon,  Idaho  and  Arizona 
each  furnishes  an  instance  of  bad  holding  power  of  a  reservoir 
built  in  lava  formation. 

Limestone  and  gypsum  formations  are  also  liable  to  caverns 
and  in  gypsum  especially  these  are  frequent,  and  are  subject  to 
rapid  enlargement  by  erosion  and  solution  by  the  waters  that 
may  leak  through  them.  Natural  basins  or  "  dry  lakes  "  are 
sometimes  formed  by  the  collapse  of  such  caverns,  and  where 
it  is  proposed  to  employ  such  basins  as  reservoirs,  careful 
study  should  be  made  of  the  geology  before  deciding  upon  its 
construction. 

Where  caverns,  crevices,  or  gravel  beds  under  the  reservoir 
afford  easy  escape  for  ground  water,  no  dependence  should  be 
placed  upon  an  overlying  blanket  of  soil  to  make  the  reservoir 
tight,  as  the  losses  by  vertical  percolation  through  such  soil 


346  STORAGE  RESERVOIRS 

will  be  too  great  for  satisfactory  results,  provided  there  is  free 
escape  for  the  percolating  waters. 

To  illustrate  this,  let  us  suppose  a  reservoir  covering  5000 
acres  of  any  average  depth  of  50  feet,  and  having,  therefore,  a 
storage  capacity  of  250,000  acre-feet,  and  that  the  ground  sur- 
face of  the  reservoir  site  is  composed  of  average  alluvial  soil, 
underlain  with  coarse  gravel,  or  with  cavernous  rock,  which 
affords'  ready  escape  for  any  water  reaching  it.  The  table  on 
p.  235  shows  a  coefficient  of  seepage  from  good  canals  of  .5 
foot  per  day.  The  seepage  loss  from  the  reservoir  would  at  that 
rate,  be  when  full,  2500  acre-feet  per  day,  or  a  rate  sufficient  to 
empty  the  reservoir  in  100  days.  The  great  head  on  a  deep 
reservoir  would  greatly  accelerate  the  rate  of  seepage,  and  the 
decline  of  the  water  would  diminish  the  wetted  area,  but  it  is 
readily  seen  that  such  a  reservoir  would  be  worthless  for  most 
purposes.  The  good  holding  qualities  of  many  reservoirs  with 
earth  bases  is  explained  by  the  fact  that  in  some  cases  they  are 
backed  by  rock  which  is  nearly  impervious,  and  in  which  such 
crevices  and  interstices  as  exist  are  soon  filled  with  water,  and 
are  of  such  minute  dimensions  as  to  make  the  escape  of  such 
water  extremely  slow.  In  other  cases  the  seepage  from  the 
reservoir  is  large  at  first,  but  having  no  ready  escape  to  an  open 
stream,  gradually  raises  the  ground  water,  until  this  rises  to  the 
surface,  and  then  we  have  a  tight  reservoir,  in  which  the  leaks 
are  sealed  with  water,  which  can  escape  only  very  slowly,  in  a 
direction  nearly  horizontal. 

4.  Leakage  from  Reservoirs. — It  is  useful  in  this  connection 
to  review  some  instances  of  reservoirs  that  have  developed 
abnormal  leakage  in  such  degree  as  to  become  nearly  or  quite 
useless. 

Tumalo  Reservoir. — This  reservoir  was  built  by  the  State  of 
Oregon  in  connection  with  the  Tumalo  Project.  Prior  to  its 
construction,  a  board  of  engineers  recommended  that  it  be  first 
built  to  only  partial  capacity,  and  that  it  be  tested  for  water 
tightness  before  heavy  expenditures  were  incurred.  It  appeared, 
however,  that  this  would  delay  completion  until  the  appropria- 
tion for  its  construction  would  lapse  into  the  general  fund, 


LEAKAGE  FROM   RESERVOIRS  347 

the  wise  recommendation  was  disregarded,  and  the  dam'  was 
completed  to.  its  full  height.  Water  was  delivered  to  the 
reservoir  through  the  feed  canal,  until  it  had  risen  about  20  feet 
above  the  outlet.  At  this  juncture  a  large  hole  developed 
in  the  bottom  of  the  reservoir  about  1000  feet  from  the  dam, 
discharging  over  200  cubic  feet  per  second,  which  soon  emptied 
the  reservoir.  This  hole  was  puddled,  and  the  water  (  again 
turned  in,  but  new  breaks  in  the  bottom  occurred,  and  it  was 
found  impossible  to  raise  the  water  again  to  the  height  first 
attained. 

The  holes  developed  varied  from  small  cracks  to  as  much  as 
50  feet  across,  and  from  10  to  30  feet  deep.  Sometimes  the 
ground  would  drop  very  suddenly.  Considerable  money  was 
spent  in  puddling  these  holes,  and  the  rapid  flow  through  them 
has  been  stopped;  but  seepage  over  the  whole  submerged  area 
occurs  to  an  extent  sufficient  to  render  the  reservoir  worthless 
for  storage. 

When  the  water  covered  a  surface  of  30  acres,  the  observed 
loss  was  from  6  to  8  inches  per  day,  which  is  normal  seepage 
through  good  earth,  but  too  rapid  for  storage  requirements. 

The  country  rock  is  of  igneous  origin  and  is  so  fissured  that 
the  ground  water  escapes  rapidly  to  the  Deschutes  river,  thus 
giving  free  vent  to  the  water  of  the  reservoir  as  fast  as  it  can 
penetrate  the  surface  soil. 

The  Deer  Flat  Reservoir  is  located  on  the  valley  near  Boise, 
Idaho.  It  is  formed  by  joining  a  series  of  low  hills  by  embank- 
ments, and  is  supplied  with  water  by  a  canal  from  the  Boise 
River.  It  is  about  10  miles  from  the  nearest  point  of  the  Boise 
River,  and  its  bottom  is  about  100  feet  above  the  river  at  that 
point.  When  full  it  covers  an  area  of  9800  acres,  and  contains 
180,000  acre-feet  of  water.  It  was  placed  in  service  in  1909, 
when  about  60,000  acre-feet  of  water  were  run  into  it,  the  greater 
part  of  which  was  lost  by  seepage,  and  not  more  than  17,000 
acre- feet  was  in  the  reservoir  at  one  time,  2500  acres  being 
then  submerged.  The  next  year  3900  acres  were  submerged, 
and  about  half  of  the  water  was  lost  by  seepage.  Many  persons 
believed  the  reservoir  was  doomed  to  failure  on  account  of 


348 


STORAGE  RESERVOIRS 


1916 


FIG.  167. — Curves  of  Seepage    from  Deer  Flat  Reservoir,   Showing  the  Improve- 
ment with  Use, 


LEAKAGE  FROM  RESERVOIRS 


349 


excessive  losses,  but  subsequent  service  showed  rapid  improve- 
ment, and  in  1917  the  seepage  losses  were  equivalent  to  less 
than  2  tenths  of  an  inch  per  day,  or  about  equal  to  the  evap- 
oration. 

TABLE  XXXIII.— DEER  FLAT  RESERVOIR  LOSSES 


Year 

Mean 
Acreage 

Sub- 

rr.erge  i 

Maxim  urn 
1     Acreage 
Sub- 
merged 

Evapora- 
tion in 
Acre-fee. 

,  Total  Loss 

in 
A  ere-  fee: 

Seepage 
Loss  in 

Acre  -feet 

AVERAGE  SEEPAGE 
Loss 

Acre-feet       Inches 
per  Acre     per  Day 

IQOQ 

L355 

2.500 

4.;50 

57.600             -         39. 

1.28 

IQIO 

3.002 

3.900 

10.500 

c  ?45j         §4.983 

* 

0-93 

I9II 

•M  59 

6.300 

15.600 

r5c.- 

I35-238 

30-3 

I.  00 

IQI2 

4-625    ; 

7.000 

16.200 

85.080 

68.889 

14.9 

0.49 

IQI3 

5.^50 

8.200 

18.400 

89.489 

71-089 

13-5          0-44 

1914 

5-337     l 

8.400 

18.700 

-  :  084 

63.384 

12.0 

0.40 

1015 

5-i-n3 

8.100 

17.900 

67.400          40.500 

97          0.32 

1916 

4-S20     i 

6.000 

16.900 

43.970          27.070            5.6          0.18 

IQI7 

4.500 

---.-: 

II.OCO 

::.4co          21.400            48          o  16 

Mean 


Total 


4-274 


6.540          14-440          78.150 


5^-;*>5o     j  120.950        704.353 


The  losses  during  1009.  IQIO  and  19 n  were  less  per  area 
submerged  than  would  be  expected  in  a  canal  in  good  tight 
soil,  and  in  the  last  two  years  this  is  reduced  to  less  than  what 
might  be  expected  from  a  canal  with  heavy  concrete  lining. 
The  steady  improvement  and  remarkable  tightness  attained 
are  due  to  the  tilling  of  the  subsoil  with  water  which  cannot 
rapidly  escape,  and  not  to  any  abnormal  tightness  of  the  soil. 

Lake  McMillan. — On  the  Pecos  River,  near  Carlsbad.  Xew 
Mexico,  is  a  project  originally  designed  and  built  by  a  private 
corporation,  in  a  region  in  which  the  country  rock  is  mainly 
gypsum,  or  sulphate  of  lime,  a  very  soft  rock  easily  eroded  by 
water,  and  to  some  extent  soluble  therein.  The  main  reservoir. 
Lake  McMillan,  is  formed  by  a  dam  across  the  Pecos  River. 
and  the  eastern  bank  of  the  reservoir  is  formed  by  a  gypsum 
bluff.  When  the  reservoir  was  filled,  the  water  freely  entered 
crevices  in  this  blutt.  and  found  ready  escape  underground. 


350  STORAGE  RESERVOIRS 

away  from  the  reservoir.  By  erosion  and  solution  these  open- 
ings steadily  enlarged  and  were  cut  down  to  the  bed  of  the  river, 
so  that  they  received  and  carried  away  the  entire  ordinary  flow 
of  the  stream  amounting  to  several  hundred  second-feet.  Num- 
erous sink  holes  also  appeared  in  the  bottom  of  the  reservoir 
into  which  the  water  escaped  in  considerable  quantities.  The 
main  leaks  in  the  gypsum  bluff  were  excluded  by  building  an 
earth  and  rock  dike  parallel  to  the  bluff  for  a  length  of  about 
4000  feet,  to  a  height  of  19  feet.  The  holes  in  the  bottom  are 
puddled  from  time  to  time,  but  not  completely  cured. 

Hondo  Reservoir. — In  the  same  valley,  near  Roswell,  N.  M., 
a  reservoir  was  formed  by  a  natural  depression  which  was 
increased  by  connecting  the  surrounding  hills  by  dikes,  and 
water  was  supplied  through  a  feed  canal.  Leaks  developed 
soon  after  the  water  was  turned  into  the  reservoir,  and  these 
rapidly  increased  by  the  enlargement  of  holes  in  the  bottom  of 
the  basin,  which  apparently  connected  with  subterranean 
caverns.  Efforts  at  puddling  the  leaks  were  una\  ailing,  and 
they  increased  to  about  200  cubic  feet  per  second,  and  the 
reservoir  had  to  be  abandoned. 

The  country  rock  in  this  region  is  composed  largely  of  gyp- 
sum, which  is  readily  eroded  and  dissolved,  and  contains  water- 
formed  caverns  which  constitute  the  seat  of  the  trouble.  The 
depression  which  forms  the  reservoir  site  may  be  due  to  the 
collapse  of  such  caverns.  Depressions  of  this  nature  are  to  be 
regarded  with  suspicion. 

Walnut  Canyon  Reservoir. — In  Walnut  Canyon,  Arizona,  a 
reservoir  was  built  to  store  water  for  railroad  uses  by  the  Atchison, 
Topeka  &  Santa  Fe  Railroad  Company,  but  although  the  dam 
was  tight  and  the  ear  them  bottom  appeared  good,  the  losses 
have  persisted  at  the  rate  of  more  than  half  a  foot  per  day  over 
the  submerged  area,  and  this  is  sufficient  to  nearly  empty  the 
full  reservoir  in  about  seven  months,  and  largely  destroys  its 
value.  The  country  rock  is  sandstone,  and  evidently  has 
enough  seams  to  carry  off  the  water  fast  enough  to  keep  the 
water  table  down,  and  keep  the  seepage  in  progress  in  nearly 
a  vertical  direction.  The  rate  of  seepage  is  not  as  great  as 


LEAKAGE  FROM  RESERVOIRS  351 

generally  occurs  from  a  well-built  canal  in  good  earth,  and  much 
less  than  a  majority  of  the  canals  in  service,  yet  it  is  great  enough 
to  destroy  most  of  the  benefits  expected  from  this  reservoir. 

The  North  Side  Twin  Falls  Irrigation  System  is  built  in  a 
country  underlain  by  lava  rock  through  which  Snake  River 
flows  in  a  gorge  several  hundred  feet  deep.  Any  crevices  in  the 
lava,  therefore,  have  communication  with  this  deep  gorge,  and 
water  in  them  can  readily  escape,  Numerous  springs  are  in 
evidence  on  the  walls  of  the  canyon.  The  Jerome  Reservoir 
is  constructed  on  this  plain,  and  fed  by  the  Main  Canal. 

In  this  reservoir  the  seepage  losses  are  about  0.85  foot  in 
depth  per  day,  or  about  what  would  be  expected  from  a  canal 
in  good  earth.  There  are  sufficient  holes  and  fissures  in  the 
underlying  rock  so  that  the  seepage  waters  have  ready  escape 
to  the  Snake  River  Canyon,  and  this  rate  of  seepage  is  there- 
fore permanent  and  continuous  so  long  as  water  is  in  the  reservoir. 
As  the  area  of  the  reservoir  is  4000  acres,  the  seepage  is  over 
2000  acre-feet  per  day  on  an  average.  This  means  a  loss  of 
over  60,000  acre-feet  per  month,  which  is  so  serious  that  the 
reservoir  is  considered  practically  worthless. 

Many  holes  developed  in  the  reservoir  bottom,  usually 
starting  from  a  badger  hole,  connecting  with  a  blow  hole  in  the 
lava,  and  enlarged  until  the  hole  in  the  lava  received  all  the 
water  it  could  carry.  Most  of  these  holes  were  less  than  6 
inches  in  diameter,  but  a  few  were  found  much  larger.  The 
smaller  holes  generally  became  clogged  with  moss  and  debris, 
and  the  rest  were  dug  down  to  a  depth  of  several  feet,  and  care- 
fully puddled  with  earth,  which  usually  made  a  permanent 
cure  of  the  particular  leak.  The  large  loss  of  water,  amounting 
to  1000  second-feet  more  or  less,  was  due  to  the  fact  that  the 
crevices  in  the  under-lying  rock  would  carry  off  the  water  as 
fast  as  it  could  filter  through  the  soil.  The  absence  of  any  water 
table,  permitting  the  continuance  of  the  seepage  in  a  vertical 
direction,  was  the  cause  of  the  reservoir's  failure,  and  this  will 
be  true  of  any  reservoir,  no  matter  how  good  the  soil  is,  if  the 
conditions  permit  the  seepage  to  travel  on  vertical  rather  than 
nearly  horizontal  lines. 


352  STORAGE  RESERVOIRS 

Tule  Lake  is  a  broad  shallow  lake  in  Northern  California. 
The  basin  was  formed  by  a  lava  flow  known  as  the  "  Modoc 
Lava  Beds."  The  lake  receives  the  entire  flow  of  Lost  River, 
which  is  disposed  of  by  evaporation  and  leaking  through  the 
lava,  which  is  very  seamy.  The  indications  are  that  the  water 
formerly  escaped  through  the  crevices  in  the  lava  as  rapidly  as 
it  entered,  and  that  the  lake  in  its  present  dimensions  is  of  very 
recent  origin,  due  to  the  clogging  of  the  seams  with  drift, 
grasses,  etc. 

A  combination  earth  and  rockfill  dam,  built  for  storage 
purposes  on  the  Zuni  River  in  New  Mexico  near  an  Indian 
Pueblo  of  the  same  name,  had  for  its  south  abutment  a  lava- 
capped  mesa,  underlain  with  several  strata  of  sand  and  clay 
which  were  exposed  in  the  margin  of  the  reservoir,  and  passing 
under  the  lava  cap,  cropped  out  in  the  canyon  below.  When 
the  reservoir  was  filled,  the  sand  strata  leaked  to  an  erosive 
extent,  and  soon  developed  a  discharge  estimated  at  5000 
cubic  feet  per  second.  This  cut  away  the  sand  and  clay, 
undermining  the  hard  basalt  cap,  which  fell  a  distance  of  7  to 
9  feet. 

It  is  often  difficult  to  recognize  in  advance  the  conditions 
that  produce  failure  of  a  reservoir  from  leakage,  and  where  they 
exist,  they  appear  to  be  generally  irremedial.  A  few  rules  of 
caution  may,  however,  be  of  use : 

1.  Avoid  reservoir  sites  adjacent  to  gypsum  deposits  and  to 
limestone  deposits  which  show  evidence  of  caves. 

2.  Reservoir    sites    in    volcanic    rock    should    be    carefully 
examined  for  the  prevalence  of  seams  or  cavities. 

3.  Coarse-grained     sandstone     should     be     regarded    with 
suspicion. 

4.  Natural  depressions  are  often  treacherous  and  should  be 
avoided  if  near  cavernous  rock  or  deep  canyons,  or  are  under- 
lain with  coarse  material  where  water  might  readily  escape. 
Under  such  conditions,  no  superficial  tightness  will  remedy  the 
trouble. 

5.  Seams  of  sand  or  gravel  in  the  reservoir  and  out-cropping 
below,  are  apt  to  cause  trouble. 


SURVEY  OF  RESERVOIR  SITES  353 

5.  Survey  of  Reservoir  Sites. — In  order  to  furnish  data  for 
comparison,  and  for  estimating  the  value  and  cost  of  contem- 
plated reservoirs,  a  careful  preliminary  survey  of  each  is  neces- 
sary. The  catchment  basin  of  each  should  be  accurately  out- 
lined and  enough  topographic  information  secured  to  show 
the  general  character  of  the  soil  and  slopes  and  the  runoff  result 
to  be  expected  therefrom.  Stream  measurements  should  be 
started  early  at  such  locations  as  will  show  the  flow  available 
for  each  site;  inquiries  of  the  inhabitants  and  others,  and  care- 
ful examinations  of  flood  marks  should  be  made  to  shed  all 
possible  light  upon  the  maximum  and  minimum  flow.  Some 
determinations  should  also  be  made  of  the  rate  of  evaporation 
to  be  used  in  each  location. 

Each  reservoir  site  considered  should  be  surveyed  topo- 
graphically, by  means  of  a  plane  table.  The  highest  point 
which  the  dam  may  reach  should  be  considered,  and  the  top 
contour  of  the  corresponding  reservoir  meandered  around  the 
entire  site,  showing  its  outlines  and  total  area.  A  main  traverse 
should  be  run  through  the  axis  or  lowest  line  of  the  site,  ter- 
minating at  the  dam  at  one  end  and  the  top  contour  at  the 
other.  These  traverses  should  be  controlled  in  elevation  by 
careful  leveling,  and  from  them  enough  intersections  and  stadia 
locations  can  usually  be  made  to  control  the  topography  of  the 
entire  site  unless  it  is  timbered,  in  which  case  additional  traverses 
may  be  necessary. 

The  scale  of  the  survey  should  be  from  1000  feet  to  an  inch 
for  small  or  medium-sized  sites,  to  2000  feet  to  an  inch  or  even 
smaller  scale  for  very  large  sites  where  the  map  on  a  large  scale 
would  be  unwieldy  and  inconvenient. 

The  contour  interval  should  be  10  feet  for  reservoirs  with 
bold  mountainous  topography,  and  5  feet  for  those  of  moderate 
slopes. 

When  the  contour  map  is  completed  the  area  enclosed  by 
each  contour  should  be  measured  by  planimeter,  and  from  these 
data  the  capacity  for  the  various  depths  may  be  computed,  and 
the  results  from  various  heights  of  dam  compared. 

In  computing  the  capacity  allowance  must  be  made  for  any 


354  STORAGE  RESERVOIRS 

dead  space  or  unavailable  capacity  below  the  bottom  of  the 
lowest  outlet,  since  the  water  below  this  cannot  be  drawn  off. 
This  space,  will  however,  ordinarily  fill  with  sediment  in  time, 
as  all  streams  carry  some  sediment  at  times,  and  in  some  cases 
the  accumulated  sediment  soon  detracts  from  the  capacity  of 
the  reservoir  and  its  disposition  becomes  a  serious  problem. 
In  general  the  streams  in  the  upper  portions  of  a  drainage  basin 
carry  less  solid  matter  in  proportion  to  volume  than  those  in 
the  lower  basin,  and  for  this  reason  reservoirs  on  the  upper 
reaches  may  be  preferable  to  those  below.  This  is  especially 
the  case  with  streams  in  the  southwestern  portion  of  the  United 
States,  which  carry  much  sediment. 

6.  Spillway  Provisions. — It  has  been  said  that  the  most 
important  feature  of  an  earthen  dam  is  the  spillway;  and  in 
the  sense  that  it  is  the  essential  feature  that  is  most  often  neg- 
lected, this  is  perhaps  true.  This  is  due  largely  to  the  extreme 
uncertainty  of  the  contingency  to  be  provided  for,  and  the 
certainty  of  disaster  if  the  water  is  allowed  to  overtop  the 
embankment.  It  is  easy  to  calculate  water  pressures  and 
allow  for  them,  and  the  permeability  of  materials  can  be  tested 
and  controlled.  But  who  can  tell  the  magnitude  or  manner  of 
occurrence  of  the  largest  flood  on  any  stream  that  the  future 
has  in  store?  Even  where  a  long  record  is  available  serious 
errors  are  possible. 

The  floods  of  1913  in  the  Miami  Valley  swept  away  structures 
that  had  stood  unharmed  for  half  a  century.  Nor  is  it  certain 
that  the  flood  of  1913  will  never  be  exceeded.  The  plans  adopted 
for  controlling  such  floods  contain  provision  for  a  much  larger 
flow. 

A  board  of  experts  once  carefully  studied  a  history  of  forty 
years  on  the  Sacramento  River  and  concluded  that  the  greatest 
flood  to  be  expected  there  was  80,000  cubic  feet  per  second. 
A  few  years  after  this  a  flood  occurred  exceeding  200,000  cubic 
feet  per  second  at  the  same  point. 

The  Sweetwater  Dam  in  Southern  California  was  built  of 
masonry  with  a  spillway  capacity  of  1500  second-feet,  which 
was  the  estimated  discharge  of  the  greatest  flood  within  the 


SPILLWAY  PROVISIONS  355 

memory  of  the  "  oldest  inhabitant."  A  few  years  after  .the 
completion  of  the  dam  it  was  overtopped  and  much  damage 
done  by  a  flood  approaching  18,000  cubic  feet  per  second.  The 
damage  was  repaired  and  spillway  capacity  provided  for  about 
20,000  second-feet.  In  1915  this  capacity  was  exceeded  and 
considerable  damage  resulted  that  could  have  been  obviated  by  a 
larger  spillway. 

Before  the  construction  of  the  Cold  Springs  Dam  in  Oregon 
a  careful  examination  was  made  of  the  valley  for  signs  of  floods, 
but  none  were  found  indicating  any  considerable  overflow  of  the 
waterway,  the  capacity  of  which  was  less  than  1000  second-feet; 
yet  during  the  construction  of  the  work,  a  heavy  rain  falling  on 
snow  caused  a  flood  of  over  6000  cubic  feet  per  second. 

These  examples  show  the  futility  of  depending  on  local 
signs  or  short  records,  or  even  upon  fairly  long  records  unless  a 
liberal  factor  of  safety  is  applied  to  their  indications.  It  would 
be  indeed  marvelous  if  an  available  record  of  ten  or  twenty  years 
should  contain  the  largest  flood  of  all  the  centuries. 

The  floods  of  1913  in  Ohio  and  Indiana  appear  from  the 
evidence  to  have  exceeded  by  40  or  50  per  cent  any  that  had 
occurred  there  for  105  years  and  to  be  considerably  greater 
than  the  next  highest  in  1805. 

In  1827  the  Ardeche  River  in  France  was  visited  by  a  flood 
much  greater  than  any  that  has  occurred  in  the  succeeding 
ninety  years.  , 

The  flood  of  1846  in  the  Loire  River  in  France  has  not  been 
equaled  since  that  date. 

Many  illustrations  might  be  cited  of  the  fact  that  extreme 
local  rainfall  or  runoff  may  occur  only  at  long  intervals  of  time 
but  are  nevertheless  likely  to  occur.  It  is  necessary,  therefore, 
in  estimating  extremes  to  be  provided  for  to  consider  the 
extremes  observed  on  areas  as  nearly  similar  as  possible,  and  to 
allow  a  factor  of  safety  sufficient  to  eliminate  all  risks  involved 
in  the  necessary  assumptions,  giving  due  regard  to  the  time  and 
geographic  extent  covered  by  the  available  data. 

Comparatively  few  measurements  of  great  floods  have  been 
made.  Systematic  stream  measurements  of  accuracy  are 


356 


STORAGE  RESERVOIRS 


TABLE  XXXIV.— EXCESSIVE  RAINFALLS 


Station 

Kiev. 

!    Aver- 
age 

An- 
nual 

Date 

INCHES   IN    i    TO  5   DAYS 

i 

2          3 

4 

5 

Lick  Observatory  

Magalia,  Cal  
Mono  Ranch,  Cal  

4209 

2320 
3210 
2750 
4975 
3216 
5350 
2250 
5280 
600 
427 

32.28 
83-12 

zoo.  14 
ioo| 
9it 
44  1 
69f 

37-22 

33-33 
3-52 

Dec.,  1884 
Jan.,  1911 
Jan.,  1906 
Mar.  1906 
Dec.,  1913 
Dec.,  1913 
Dec.,  1910 
Jan.,   1916 
Jan.,   1916 
Jan.,   1916 
Jan.,   1911 
July,  1914 

10.86 
11.50 
10.40 
10.35 

10.00 

11.24 
12.95 

16.81 

6.15 
3-75 

9-05 

*9.IQ 

14-75 
!3-23 
13.60 
17.24 
15-99 
22.64 
9-95 

15-47 
14-23 
14-25 
20.  76 

18.79 
25.66 
13-30 

22.  6l 
20.  l6 

26.87 

16.15 

23.12 

20.  27 
27.32 
16.31 

Helen  Mine,  Cal  
Inskip,  Cal    . 

West  Branch,  Cal  
Nellie,  Cal  

Rialto,  Cal 

Squirrel  Inn,  Cal  

Los  Gatos  Cal 

Needles,  Cal  

*  Precipitation  probably  occurred  in  two  or  more  days, 
f  Average  annual  rainfall  approximate. 


Station 

Aver- 
age 
An- 
nual 

Date 

INCHES  OF   RAINFALL  IN 

i  day 

2  days  3  days^  days 

5  days 

Monterey,  Mexico  

25.0 

Aug.,  1913 
June,  1886 
July,  1916 
Jan.,  1913 
Nov.,  1909 
Aug.,  1865 
Aug.,  1866 
June,  1876 
Sept.,  1879 
Oct.,  1846 
June,  1886 
May,  1835 

Aug.,  1899 
Oct.,  1893 
Feb.,  1893 
Oct.,  1844 
May,  1889 

ii  -3 
21.4 

22.  2 
20.6 

15-8 

17.6 

18.8 
48 

21.6 
II4-5 

Alexandria,  La. 

Alapass   N   C 

8.0 
40.* 

Montell,  Texas  
Jamaica.  . 

Hyderbad,  India  .... 

10.  2 
20.0 
40.8 

35-o 

20.6 

16.0 

12.0 

18.0 

35-5 
29.4 

30-7 
20.4 

8-3 
12.7 
10.6 
i5-o 
31-8 

21.8 

35-o 
8.8 

34-0 

r5-4 
36.0 

Dorbajee,  India  

Cherrapanji,  India  
Purneah.  N.  Bengal. 

50.00 
50.8 

33-i 
46.0 

30.0 
61.6 

72.3 
88.1 

Madras,  India  
Bombay,  India. 

Calcutta,  India  
Himalaya  Foothills,  India.  .  .  . 
Tabana,  Japan. 

Sama,  Japan  .    .    !  

Crohamhurst,  Queensland 

Port  Jackson,  N.  S.  W  
Sidney,  N.  S.  W  
Windsor,  N.  S  W 

Newcastle,  N.  S.  W  
Delanason,  Figi  I. 

Mar.,  1871 
Mar.,  1871 
Dec.,  1897 
May,  1881 
July,  1911 
Apr.,  1883 

Neydunkeni,  Ceylon  
Hongkong,  China  

Baguio,  P.  I 

Rio  Janeiro,  Brazil  

*  Average  annual  rainfall  approximate. 


SPILLWAY  PROVISIONS 


TABLE  XXXIV.— EXCESSIVE  RAINFALLS.— Continued. 


357 


[Station 

Aver- 
age 
An- 
nual 

Date 

INCHES  IN   i  TO  5   DAYS 

i 
7-8 

13-7 
14-7 
8.8 
12.4 
7-3 
5-6 
10.5 

6.2 

10.6 
6.9 
i?-S 
5-4 
2  .  05  ir 
n.  in  3 
in.  in 
in.  in 
in.  in 
3  in.  in 
in.  in 

2 

3 

4 

s 

San  Francisco,  Cal  
Philadelphia,  Pa.. 

Dec.   19,  1866 
Sept.  22,  1882 

9-57 

7.8  in 
3  in. 
i.  in  i 
hours 
i  houi 
14  hoi 
5  houj 
30  m 
c  year. 

.  in  4 
in  2  h< 
hour. 

irs. 
•s. 
nutes 

lours 
Durs. 

Mayport  Fla 

Jewell,  Md  
Greytown,  Nic 

July  27,  1897 
Dec.     5,  1892 
T\ov.    4,  1899 
Nov.  17,  1906 
Dec.     3,  1906 
Dec.     3,  1906 
Dec.     3,  1906 
Sept.  3,   1900 
1901 
Oct.  13,   1901 
Aug.    3,  1898 

Aug.    22,    1899, 

Aug.,  1843,  1  6  i 
Aug.,  1906,  9.3 
June,  1871,  3.9 
May,  1868,  1.5 
Feb.  n,  1894,  , 
700 

Grey  town,  Nic  
La  Boca,  C.  Z.  . 

Culebra,  C.  Z  
Gatun,  C.  Z  
Empire,  C.  Z  
Santiago,  Cuba  

Matanzas,  Cuba. 

Guantanamo,  Cuba  

Philadelphia,  Pa  

Boston,  Mass  

Concord,  Penn. 

Guinea,  Va  

Galveston,  Texas  

Ft  McPherson  Neb 

Sydney,  N.  S.  W  
Himalaya  Foothills,  India. 

mostly  of  recent  origin  and  the  points  of  measurement  are  still 
comparatively  few,  and  it  has  frequently  happened  that  the 
really  destructive  floods  have  destroyed  the  facilities  for  mea- 
surement, and  the  extremely  rare  opportunities  for  measuring 
great  floods  are  thereby  sometimes  lost. 

On  the  other  hand,  rainfall  measurements  are  far  more  widely 
distributed,  have  been  continued  for  a  much  longer  period, 
and  in  general  may  be  regarded  as  more  reliable  than  flood 
measurements  of  streams,  on  account  of  their  greater  simplicity. 

For  these  reasons  we  are  often  compelled  to  rely  more  upon 
rainfall  records  than  upon  measurements  of  runoff  for  estimating 
the  magnitude  of  floods  for  which  we  must  provide  spillway 
capacity. 

A  study  of  the  longest  available  rainfall  records  shows  that 
it  is  possible  here  and  there  to  select  consecutive  periods  of  a 


358  STORAGE  RESERVOIRS 

half  century  or  so  which  contain  no  excessive  precipitation 
approaching  that  shown  by  other  parts  of  the  same  record. 
It  is  seldom,  however,  that  a  period  is  found  in  which  the  maxi- 
mum of  1000  years  exceeds  very  much  that  shown  by  any 
period  of  100  or  200  years. 

Professor  Kuichling  has  compiled  and  published  a  list  of 
high  discharges  from  which  the  most  extreme  floods  have  been 
selected  and  condensed  into  a  table  along  with  other  data, 
which  are  given  in  the  last  chapter  of  this  book. 

7.  Outlet  Works.— One  of  the  most  vulnerable  features  of  an 
earthen  dam  is  the  provision  for  drawing  water  from  the  reservoir 
through  or  past  the  dam.  The  danger  consists  in  the  fact  that 
unless  elaborate  precautions  are  taken,  the  conduit  presents  a 
convenient  path  for  the  percolation  of  water,  which  may  carry 
earth  with  it,  and  gradually  enlarge  the  opening  until  a  breach 
is  made  and  the  dam  destroyed. 

The  outlet  conduit  is  generally  of  concrete  although  cast-iron 
pipe  is  sometimes  used  for  small  reservoirs.  In  a  few  cases 
wooden  conduits  have  been  provided,  but  this  is  bad  practice, 
as  any  decay  at  once  opens  passage  for  leakage. 

It  is  best  to  locate  the  conduit  in  an  open  trench  cut  in  rock, 
hardpan  or  clay,  and  to  build  the  concrete  directly  against  the 
sides  and  bottom  of  the  trench,  which  will  thus  form  a  good  bond 
between  the  artificial  work  and  the  natural  ground.  The 
trench  above  the  conduit  should  be  filled  with  selected  material 
carefully  puddled  and  rammed  in  place.  The  conduit  should  be 
provided  with  wide  collars  or  diaphragms  of  concrete,  extending 
entirely  around  the  circumference,  and  these  should  also  be 
built  against  the  natural  material  in  place  as  far  as  possible. 
The  collars  may  be  of  any  convenient  thickness,  as  i  or  2  feet, 
and  should  extend  into  the  foundation  and  the  fill  at  least  3 
feet  beyond  the  outer  lines  of  the  conduit  proper.  The  masonry 
in  contact  with  the  natural  and  filled  material  should  be  rough 
and  corrugated  and  every  precaution  taken  to  form  a  tight  bond 
between  them,  as  this  is  one  of  the  most  difficult  as  well  as  the 
most  important  problems  in  connection  with  earth  dam  con- 
struction. 


OUTLET  WORKS  359 

The  valves  controlling  the  admission  of  water  to  the  conduit 
should  be  placed  at  the  upper  end,  at  or  near  the  upstream  toe 
of  the  embankment,  and  some  means  should  be  provided  by 
which  access  may  be  had  to  the  valves  at  any  time  that  they 
might  need  attention. 

This  position  of  the  valves,  if  ordinary  valves  are  used, 
requires  a  tower  built  over  them  at  a  distance  from  the  crest 
of  the  dam,  which  must  be  reached  by  means  of  a  bridge.  The 
bridge  could  be  avoided  and  the  tower  much  cheapened  by 
placing  the  valves  near  the  axis  of  the  dam,  but  this  is  objection- 
able, as  it  would  admit  water  to  half  the  conduit  under  pressure 
of  the  full  head  in  the  reservoir,  and  any  leaks  would  introduce 
water  into  the  heart  of  the  dam,  and  might  in  time  cause  satura- 
tion and  softening  of  the  interior  of  the  dam  and  give  rise  to 
danger  that  might  otherwise  be  avoided.  The  controlling 
valves  may  be  of  the  balanced  type  controlled  by  water  pressure 
as  described  on  p.  365.  The  pipe  controlling  the  leakage  which 
governs  the  position  of  the  valve  may  be  led  through  the 
conduit  or  up  the  slope  of  the  dam,  and  thus  avoid  building  a 
tower  in  the  reservoir  for  control  purposes.  Such  a  control  is  in 
successful  use  on  the  Owl  Creek  Dam  in  South  Dakota. 

Slide  valves  may  be  installed  on  the  upper  end  of  the  conduit 
at  the  toe  of  the  dam,  placed  in  the  plane  of  the  water  slope  of 
the  dam,  sliding  in  grooves  and  attached  to  gate  stems  following 
up  the  slope  to  the  top  of  the  dam,  where  they  are  controlled 
by  gate  stands  on  top  of  the  dam.  This  type  of  control  does 
not  always  give  satisfaction.  The  stem  following  the  slope 
of  the  dam  is  long  and  requires  a  number  of  supports  to  hold 
it  in  line.  These  are  placed  on  the  earth  fill  and  are  subject  to 
unequal  settlement,  and  unless  protected,  to  the  attacks  of  ice, 
of  drift  and  of  waves.  It  is  not  surprising  that  they  often  get 
out  of  line  and  become  difficult  to  operate. 

A  successful  valve  of  this  type  is  in  use  on  the  Conconully 
reservoir  of  the  Okanogan  project  in  Washington,  which  is  closed 
by  an  earth  dam  83  feet  high.  The  outlet  is  a  circular  conduit 
of  reinforced  concrete  4  feet  6  inches  inside  diameter.  This  is 
controlled  by  a  cast-iron  valve  gate  3  feet  6  inches  in  diameter, 


360 


STORAGE  RESERVOIRS 


placed  in  a  gate-well  7  feet  square  for  access,  and  operated  from 
a  gate  house  62  feet  above  by  a  steel  shaft  and  geared  wheel. 
This  shaft  is  supported  in  an  inclined  tunnel  5  feet  10  inches  in 
section  and  103  feet  in  length,  the  reinforced  concrete  walls  of 
which  are  from  15  to  24  inches  in  thickness  (Fig.  168). 


X  Steel  Rote 
2'c.toc. 


SECTION    E-£ 


FIG.  1 68. — Gate  House,  Conconully  Dam,  Wash. 

If  the  Ensign  type  of  balanced  valve  be  used,  see  Fig.  172, 
the  control  pipe  may  pass  through  the  conduit,  and  thus  be 
thoroughly  protected,  and  does  not  require  any  special  alinement. 
The  balanced  valve  moving  with  little  friction  is  less  likely  to 
get  out  of  order  or  require  attention  than  ordinary  slide  valves. 

A  simple  outlet  gate  (Fig.  169),  designed  by  Mr.  J.  D. 
Schuyler  to  be  built  on  the  face  of  Fay  reservoir  dam,  is  adapted 


OUTLET  WORKS 


361 


SECTIONAL. BOTTOM  PLAN. 


ENLARGED  SECTION  OF  FRAME 
AND  BOLIING.EAR. 


FIG.  169. — Vertical  Lift  Outlet  Gate,  Fay  Lake  Reservoir,  Arizona. 


362 


STORAGE  RESERVOIRS 


to  closing  an  outlet  of  either  circular  or  rectangular  form.  The 
gate  is  hung  on  its  center  by  one  heavy  lug,  over  which  the  stem 
is  placed,  expanded  to  the  form  of  a  flat  eye-bolt,  having  sufficient 
play  to  enable  the  gate  to  accommodate  itself  to  its  seat  freely,  to 
which  it  is  forced  by  inclined  planes  on  six  lugs  and  guides.  The 
frame  of  the  hoisting  apparatus  rests  on  top  of  the  masonry,  to 
which  it  is  anchored,  and  the  nut  and  beveled  gear  are  of  hard 
brass.  Ball  bearings  are  fitted  under  the  nut,  and  a  light  capstan 
wheel  takes  the  place  of  the  ordinary  crank,  rendering  the  gate 
easily  handled  under  the  maximum  head  of  25  feet. 


A.  B. 

FIG.  170. — Valve-plugs,  A,  Sweetwater,  and  B,  Hemet  Dams. 


Two  other  very  simple  devices  designed  by  the  same  engineer 
are  illustrated  in  Fig.  170.  Each  of  these  consists  of  a  simple 
cast-iron  plug  let  into  the  top  of  the  pipe,  the  end  of  which  is 
bent  upward  to  receive  it.  The  plug  is  held  in  position  by  the 
pressure  of  water,  and  is  opened  by  a  chain  operated  from  above 
by  a  windlass. 

Butterfly  and  Needle  Valves. — One  of  the  safest  and  most 
satisfactory  forms  of  outlet  for  delivering  water  through  an 
earthen  dam  is  that  in  use  at  the  Minitare  Dam  of  the  U.  S. 
Reclamation  Service,  in  North  Platte  Valley,  Nebraska.  It 
consists  of  a  concrete  tube  with  arched  top  and  invert,  built 
in  cut  averaging  somewhat  less  than  the  height  of  the  tube, 
or  about  8  feet,  with  cut-off  collars  at  frequent  intervals  on  the 
outside  to  check  percolation  along  the  tube.  Inside  this  tube 


OUTLET  WORKS 


363 


u 

1 

ri 

*£-^" 

-j 

Ele 

Elc 

K—  ?'o"  > 
^.4070  b^:;v 

.  10(10  'r<f  0.'-.    ".." 

t  :-  v? 

^  Elcv.4060 


Elev.4058 


I  Elev.40T>4  ll^llli 

\ 

I 

""  --7-0\x<  -.9 

— V280 -'— 

AXIS' OF  VALVE  AND  OUTLET 'TUBE\  , ^^' 


FIG.  171. — Outlet  Works,  Lahontan  Dam,  Carson  River,  Nevada. 


364  STORAGE  RESERVOIRS 

are  laid  side  by  side  two  heavy  steel  pipes,  each  30  inches  in 
diameter,  with  their  upper  ends  projecting  through  a  heavy 
concrete  bulkhead  into  the  reservoir.  Just  back  of  this  bulk- 
head each  pipe  is  equipped  with  a  butterfly  valve,  which  being 
approximately  balanced,  is  easily  operated  under  full  head, 
and  is  use'd  as  an  emergency  valve.  Its  operating  chamber  is 
an  enlargement  of  the  concrete  tube.  The  service  valves  are 
installed  at  the  downstream  ends  of  the  pipes,  and  are  of  the 
needle  valve  type,  similar  in  design  to  that  shown  on 

P.  368. 

The  tunnel  is  drained  at  the  lower  end,  and  room  is  afforded 
for  careful  inspection  of  the  pipes  throughout. 

In  this  arrangement  there  is  no  opportunity  for  water  to 
escape  by  leakage  into  the  interior  of  the  dam,  any  leakage  of 
pipes  being  led  away  by  the  drainage  of  the  tunnel,  and  being 
also  accessible  for  repair. 

Although  the  butterfly  valves  cannot  be  made  entirely 
tight  under  high  heads,  they  can  be  made  nearly  so  if  carefully 
installed,  and  being  simple  and  seldom  operated  are  not  likely 
to  get  out  of  order.  By  closing  one  of  them,  the  needle  valve 
on  the  lower  end  of  the  same  pipe  may  be  taken  apart  and 
repaired  at  any  time,  even  while  the  other  needle  valve  is  dis- 
charging water.  No  gate  tower  in  the  reservoir  is  necessary 
with  its  menace  from  ice  and  waves.  Altogether  this  is  regarded 
as  the  most  satisfactory  regulating  system  connected  with  an 
earthen  dam  yet  tried. 

Balanced  Piston  Valve. — A  type  of  valve  used  on  several 
of  the  reservoirs  of  the  Reclamation  Service,  Fig.  17 2,  has  shown 
especial  suitability  for  use  where  it  is  necessary  to  draw  large 
quantities  of  water  under  high  heads.  It  utilizes  the  enormous 
water  pressures  to  open  and  close  the  valve.  It  consists  of  a 
steel  cylinder  closed  at  the  outer  or  downstream  end,  in  which 
slides  a  piston,  the  inner,  end  of  which  forms  a  needle,  operating 
to  regulate  the  amount  of  water  discharged  and  closing  like 
a  check  valve.  The  piston  may  be  removed  by  removing  the 
cylinder  head.  It  is  kept  in  alinement  with  the  axis  of  the 
cylinder  by  bronze  guides. 


OUTLET  WORKS 


365 


366 


STORAGE  RESERVOIRS 


FIG.    173. — Outlet   Conduit,    Keechelur   Dam,   Washington,    Showing   Concrete 
Cut-off  Collars,  Corewall  and  Track  for  Backfilling  on  Left. 


FIG.  174. — Butterfly  Valve,  Minitare  Dam,  Nebraska. 


OUTLET  WORKS 


367 


It  is  opened  and  closed  by  the  regulation  of  the  pressure  of 
water  behind  the  main  piston,  the  pressure  being  supplied  by  the 
restricted  leak  past  the  piston,  and  relieved  by  a  drain  or  control 
pipe  leading  out  from  the  cylinder  head.  To  open  the  valve  the 
pressure  on  the  piston  is  reduced  by  opening  the  outlet  of  the 


SELL 


DOWNSTREAM  ELEVATION  VERTICAL  SECTION  ON  C.'L, 

FIG.  175. — Elevation  and  Section  of  Butterfly  Valve. 

control  pipe.  As  long  as  this  discharges  freely  the  valve  will 
continue  to  move  until  completely  open,  and  it  may  be  stopped 
at  any  point  partially  open  by  properly  regulating  the  leakage 
through  the  control  pipe.  To  close  the  valve,  the  outlet  from 
the  control  pipe  is  closed  and  pressure  applied  from  a  tank  far 
above  the  reservoir  to  start  the  piston,  after  which  ,it  will  slowly 


368 


STORAGE  RESERVOIRS 


close  itself,  the  rate  of  movement  depending  on  the  volume  of 
leakage  around  the  piston. 


19 


FIG.  176.— Needle  Valve  in  Outlet  Conduit,  Minitare  Dam,  North  Platte  Valley, 

Nebraska. 


In  order  to  give  positive  and  accurate  regulation  of  discharge 
from  the  reservoir  a  positive  control  is  also  provided  as  shown 


OUTLET  WORKS  369 

in  the  drawing.  The  leakage  is  regulated  by  a  movable  sleeve 
fitting  over  a  conical  seat  which  stops  the  leakage  when  closed 
and  when  opened  permits  the  escape  of  water,  thus  removing  the 
pressure  from  that  side  of  the  piston,  causing  the  valve  to  open. 
The  valve  thus  follows  the  sleeve,  maintaining  just  enough  area 
between  the  sleeve  and  the  conical  seat  to  regulate  the  leakage  to 
the  quantity  required  for  balance.  The  sleeve  being  movable  at 
will,  by  means  of  a  hand-wheel,  rod  and  screw,  the  position  of  the 
valve  can  be  accurately  controlled.  An  indicator  is  provided  to 
show  the  position  of  the  valve  at  any  time. 


CHAPTER  XVI 
SEDIMENTATION    OF    RESERVOIRS 

ALL  natural  streams  erode  their  channels  to  some  extent, 
and  carry  more  or  less  silt  in  suspension  and  roll  along  their  bot- 
toms sand  and  gravel.  Where  a  dam  is  built  across  the  stream 
and  the  water  impounded,  the  sediment  settles,  and  may  in  time 
seriously  impair  the  reservoir  capacity  if  not  removed.  In 
high  mountainous  regions  where  the  slopes  are  protected  from 
erosion  by  forests,  and  where  the  water  comes  chiefly  from 
springs  or  melting  snows,  the  streams  are  usually  clear  and  very 
little  sediment  is  carried.  On  such  streams  the  silt  problem 
is  generally  considered  negligible  or  so  far  in  the  future  as  to  be 
met  by  constructing  new  reservoirs  when  needed.  Lower  down 
the  same  stream  may  accumulate  more  sediment,  and  this 
problem  may  assume  considerable  importance. 

In  other  regions  less  protected  by  vegetation  and  subject  to 
torrential  rains,  as  in  the  southwestern  part  of  the  United  States, 
the  streams  carry  enormous  quantities  of  solid  matter,  and  it 
becomes  a  serious  question  whether  any  given  storage  project 
is  feasible  in  view  of  the  rapidity  with  which  the  capacity  will  be 
destroyed  by  filling  with  detritus.  The  Colorado  and  the  Rio 
Grande  are  typical  streams  of  this  class. 

Where  it  is  feasible  to  locate  the  reservoir  off  the  stream, 
and  conduct  the  water  to  it  through  a  feed  canal,  it  may  be 
possible  to  discard  most  of  the  coarse  material  by  means  of 
settling  basins  and  scouring  sluices,  but  these  require  much 
attention,  waste  much  water  and  are  not  very  effective  in 
eliminating  the  finer  silt. 

The  problem  involved  by  the  sedimentation  of  reservoirs 
constructed  on  silt-bearing  streams  is  one  which  has  received 

370 


SEDIMENTATION  OF  RESERVOIRS 


371 


much  study,  and  various  theories  have  been  advanced  for  its 
solution,  but  none  of  them  have  been  proved  out  in  practice. 

Several  efforts  have  been  made  to  determine  a  reliable  factor 
to  express  the  relation  between  the  dry  weight  of  silt  obtained 
by  observation,  and  the  volume  of  the  same  silt  as  it  would  lie 
in  the  bottom  of  a  reservoir,  the  question  being,  "  What  is  the 
dry  weight  of  a  cubic  foot  of  silt  deposited  in  a  large  reservoir 
by  sedimentation  of  the  flood  waters  of  the  stream?" 

The  following  table  shows  the  results  of  the  four  most  reliable 
of  these  attempts: 

TABLE  XXXV 


Observer 

Weight  of  Cubic 
Foot  of  Wet 
Deposited  Silt 

Dry 
Weight 

Specific 
Gravity 

Follett  

C-2      O 

Coghlan. 

I  O4.   7 

Q2      7 

2   64 

Hughes  

80    ^ 

76  I 

2    << 

Lavv«on  

86  o 

2    60 

Averaging  the  above  results,  we  have  77  pounds  as  the 
average  dry  weight  of  a  cubic  foot  of  silt  deposited  in  a  reservoir. 
This  however,  can  be  taken  as  only  a  very  rough  guide,  as  would 
be  inferred  from  the  wide  discrepancy  in  the  results  quoted. 

The  variation  is  doubtless  due  in  part  to  actual  difference  in 
character  and  weight  of  the  different  samples  of  silt  tested.  It  is 
probable  that  a  more  important  reason  is  the  difference  in 
judgment  of  the  different  observers  as  to  what  constitutes  a 
sample  of  silt  representative  of  conditions  in  the  bottom  of  a 
large  reservoir,  under  the  pressure  of  overlying  mud  and  water. 
Such  conditions  will  vary  widely,  and  we  cannot  hope  to  obtain 
any  results  that  would  serve  as  more  than  a  rough  guide  for  future 
estimates. 

Systematic  observations  of  silt  carried  in  suspension  by  the 
waters  of  the  Rio  Grande  have  been  made  by  the  United  States 
Government,  from  1897  to  the  present  time.  These  observations 
up  to  and  including  1912  were  carefully  studied  by  W.  W.  Follett 
and  the  results  obtained  are  summarized  in  the  following  table: 


372  SEDIMENTATION  OF  RESERVOIRS 

TABLE  XXXVI.— SILT  IX  RIO  GRAXDE  PASSING  SAN  MARCIAL,  N.  M. 


Year 

Acre-feet  Water 

Per  Cent  Silt 

Acre-feet  Silt 

1897 

2,215,953 

1.72 

38,051 

1898 

960,981 

1-55 

14,858 

1899 

239,434 

2.14 

5,127 

1900 

467,703 

2.02 

9,459 

1901 

656,252 

2.82 

18,503 

1902 

200,729 

3-05 

6,123 

1903 

1,272,069 

0-97 

12,319 

1904 

700,796 

2-37 

16,838 

1905 

2,422,008 

0.78 

18,875 

1906 

1,563,737 

0.89 

13,901 

1907 

2,157,709 

I  .  II 

23,889 

1908 

774,109 

2.00 

15,469 

1909 

1,279,934 

I-5I 

19,318 

1910 

852,692 

o.  76 

6,520 

1911 

1,799,733 

4.14 

74,563 

1912 

1,499,614 

1-47 

22,018 

Total  

19,072,453 

315,832 

Mean  

1,192,028 

1.66 

19,739 

These  silt  determinations  were  made  by  taking  samples  of  the 
muddy  water  as  found  flowing  in  the  river,  and  removing  the 
silt  by  settlement  and  filtration,  drying  at  60°  C.  and  weighing 
it.  The  percentages  are  by  volume,  and  are  based  upon  a  dry 
weight  of  53  pounds  for  a  cubic  foot  of  wet  sediment  in  place 
in  the  reservoir. 

This  factor  of  53  was  found  by  taking  the  dry  weight  of  a 
3 -inch  cube  of  wet  silt  from  a  slough  where  a  body  of  flood  water 
had  stood  until  the  sediment  settled,  the  water  evaporated,  and 
the  silt  began  to  shrink  from  the  drying  process. 

These  observations  show  that  if  a  reservoir  of  300,000  acre- 
feet  capacity  had  been  constructed  in  1897,  it  would  have  been 
practically  filled  with  sediment  several  years  ago,  unless  this 
had  been  somehow  removed.  They  show,  further,  that  any 
reservoir  constructed  on  this  stream  would,  unless  prevented, 
have  its  capacity  seriously  impaired  in  a  time  so  short  as  to 
present  a  problem  of  importance.  This  must  be  solved  before 


SEDIMENT  ROLLED  ALONG    THE  BOTTOM  373 

deciding  upon  the  construction  of  an  expensive  storage  project, 
where  thousands  of  homes  are  to  be  established  through  its 
agency  which  will  be  destroyed  if  it  fails  of  its  purpose. 

The  measurement  of  sediment  in  the  Colorado,  Gila  and 
Pecos  Rivers  reveal  similar  problems  concerning  storage  projects 
thereon,  and  the  same  may  be  said  in  some  degree  of  many  other 
streams  in  this  and  other  countries. 

A  study  of  scattered  observations  of  silt  carried  by  the  Gila 
River  made  by  D.  E.  Hughes,*  leads  him  to  the  conclusion 
that  its  water  carries  an  average  of  1.3  per  cent  of  its  volume 
of  solid  matter. 

Various  reservoirs  in  Europe,  Asia  and  America  have  had 
their  capacity  largely  destroyed  by  the  accumulation  of  mud 
and  sand. 

From  a  consideration  of  all  available  results  of  experiment 
in  India  and  America,  Etcheverry  concludes  that: 

1.  One  cubic  foot  of  saturated  silt  settled  in  a  tube  for  one 
year,  contains  about  30  pounds  of  dry  silt.     The  per  cent  by 
volume,   of  saturated  silt  is  equal  to  the  per  cent  by  weight 
multiplied  by  2.1. 

2.  One  cubic  foot  of  moist  silt,  as  deposited  under  natural 
conditions  in  a  river  or  canal  or  on  a  field,  will  contain  about 
50  pounds  of  dry  silt.     For  this  condition  the  per  cent  by  volume 
of  moist  silt  is  equal  to  the  per  cent  by  weight  multiplied  by  1.2. 

3.  One  cubic  foot  of  dried  silt  will  weigh  about  90  pounds. 
The  above  results  cannot  be  considered  accurate  for  any 

particular  silt  sample,  nor  for  any  particular  stream,  as  individual 
cases  vary  widely.  It  is,  however,  about  as  good  a  statement 
of  averages  as  present  knowledge  will  afford. 

2.  Sediment  Rolled  along  the  Bottom. — In  addition  to  the 
sediment  which  is  held  in  suspension  and  carried  by  the  current 
of  the  stream  there  may  be  larger  and  heavier  particles  of  sand 
which  are  too  heavy  to  be  held  in  suspension  but  which  under 
the  influence  of  flowing  water  gradually  move  downstream 
along  the  bottom.  This  frequently  happens  in  streams  of  per- 
fectly clear  water,  and  careful  observations  of  such  streams  will 

*  House  Doc.  791,  6$d  Congress,  2d  Session. 


374  SEDIMENTATION  OF  RESERVOIRS 

show  the  sand  in  small  knolls  or  dunes  on  the  bottom  of  the 
stream.  The  grains  of  sand  on  the  surface  -gradually  move 
down  the  stream.  The  small  sand  bars  are  usually  very  gentle 
in  slope  on  the  upstream  side  and  steep  on  the  downstream 
side.  The  moving  grains  of  sand  are  carried  slowly  up  the 
slope  of  the  little  bar  or  dune  and  reaching  the  summit  are 
dropped  on  the  downstream  side,  forming  on  that  side  a  slope 
usually  about  45  degrees  near  the  top,  flattening  slowly  toward 
the  bottom,  while  the  slope  on  the  upstream  side  may  be  5  or 
6  to  i. 

Where  the  major  portion  of  the  solid  matter  carried  by  the 
stream  is  in  the  form  of  sand  this  material  moving  on  the  bottom 
becomes  an  important  element  in  measuring  total  solids.  Where 
the  eroded  material  is  mainly  clay  the  amount  of  sediment 
on  the  bottom  may  be  insignificant.  The  quantity  of  all 
material  carried  can,  of  course,  be  accurately  measured  by 
impounding  it,  but  aside  from  this  method  little  effort  has  been 
made  to  measure  this  in  flowing  streams.  The  only  attempt 
of  this  kind  on  any  large  scale  was  that  made  by  the  Nicaragua 
Canal  Commission  in  1898  upon  the  streams  in  Nicaragua  in 
connection  with  the  investigation  of  an  inter-oceanic  canal. 
The  method  devised  was  as  follows: 

A  galvanized  sheet-iron  pan  was  provided  (see  Fig.  177), 
i  meter  square  and  8  inches  deep,  with  one  side  hinged  so  that 
it  could  be  opened  to  lie  in  the  same  plane  as  the  bottom  of  the 
pan,  and  a  weight  and  stays  were  provided  to  hold  it  in  this 
horizontal  position.  Four  chains,  attached  one  to  each  corner 
of  the  top  of  the  pan,  met  about  4  feet  above  the  pan,  and  united 
in  a  ring,  and  the  whole  was  suspended  from  a  cable  stretched 
across  the  river,  with  the  door  open  upstream.  An  anchor  was 
thrown  about  100  feet  upstream  to  hold  the  pan  firmly 
in  position,  while  it  was  gently  lowered  from  the  cable  by  means 
of  a  rope  from  shore,  working  in  tackle  blocks.  The  pan  was 
allowed  to  settle  firmly  on  the  bottom,  and  to  remain  for  a 
limited  time,  usually  one  hour.  The  attempt  is  to  cause  the 
minimum  disturbance  of  natural  conditions  in  the  stream,  and 
to  intercept  and  hold  in  the  pan  the  sediment  traveling  along 


SEDIMENT  ROLLED  ALONG   THE  BOTTOM  375 

the  bottom  in  the  section  it  occupies.  When  it  is  desired  to 
close  the  observation,  a  small  copper  wire  which  has  been  fas- 
tened to  the  open  door  and  passed  through  the  ring  above  the 
pan,  is  stoutly  pulled  until  it  raises  the  lid  from  the  bottom  of 
the  stream,  whereupon  the  current  catches  and  slams  the  lid 
shut,  where  it  is  automatically  fastened  by  a  latch  on  each  side. 
Then,  by  means  of  a  windlass  on  shore,  the  pan  is  hoisted  and 
brought  to  land,  and  the  entrapped  sediment  measured. 

There  is  nothing  about  this  operation  to  increase  the  motion 
of  sediment  along  the  bottom  into  the  pan,  so  it  is  thought  that 


FIG.  177. — Trap  for  Measuring  Sand  Rolling  on  Bottom  of  Stream. 

results  can  never  be  too  large.  On  the  other  hand  some  sand 
may  pass  under  the  edge  of  the  lid,  when  the  bottom  of  the  river 
at  this  point  is  marred  with  local  inequalities.  This  is  supposed 
to  be  one  cause  of  the  small  results  on  certain  days,  when  other 
observations  immediately  before  or  after,  give  large  results. 
Another  persistent  source  of  error  of  unknown  magnitude  is 
the  washing  out  of  the  sediment  by  the  current  over  the  weir 
formed  by  the  back  of  the  pan.  To  test  the  importance  of  this 
theoretical  possibility,  a  temporary  partition  was  placed  in  the 
pan,  perpendicular  to  the  current,  and  nearly  as  high  as  the 


376  SEDIMENTATION  OF  RESERVOIRS 

sides  of  the  pan,  the  theory  being  that  if  all  sediment  were 
stopped  by  the  partition  and  deposited  in  front  of  it,  that  would 
be  good  evidence  that  in  the  absence  of  the  partition  all  would 
be  stopped  by  the  back  of  the  pan,  and  none  lost.  In  the  first 
experiment  more  sediment  was  deposited  behind  than  in  front 
of  the  partition,  and  the  quantity  that  passed  out  of  the  pan  is 
unknown.  This  result  was  essentially  repeated  for  most  of  the 
experiments,  showing  conclusively  that  more  or  less  sediment 
is  carried  out  over  the  back  of  the  pan  by  the  scour  which  it 
occasions.  It  is  important  to  bear  this  fact  in  mind,  when 
studying  the  results,  for  it  is  certain  that  the  results  are 
quantitatively  too  small,  and  should  be  regarded  as  showing 
that  large  quantities  of  sediment  are  traveling  on  the  bed  of  the 
stream,  and  as  roughly  indicating  the  relative  amount. 

3.  Removal  of  Silt  from  Reservoirs. — The  great  Assuan  Dam 
in  Egypt,  forms  a  reservoir  on  the  Nile,  which  has  a  very  large 
discharge  and  carries  great  volumes  of  silt.  The  large  capacity 
of  the  reservoir  is  formed  mainly  by  the  very  slight  slope  of  the 
river,  so  that  the  dam  causes  slack  water  for  a  distance  of  over 
40  miles  up  the  river,  making  a  long  narrow  reservoir,  with  no 
very  wide  valley  submerged.  The  dam  is  provided  with  180 
large  sluices,  and  during  the  rising  flood  each  year,  when  the 
river  is  carrying  most  sediment,  the  sluices  are  left  open,  and  the 
rushing  torrent  carries  its  load  through  the  reservoir  and  also 
scours  out  a  portion  of  the  sediment  deposited  the  previous 
year.  As  the  flood  declines  in  volume  it  carries  less  sediment, 
and  the  sluice  gates  are  then  closed  and  the  waters  stored. 
The  sediment  deposited  during  the  storage  period  is  largely 
washed  out  by  the  first  part  of  the  next  year's  flood. 

This  program  seems  to  be  effective  in  preserving  sufficient 
storage  capacity  for  present  needs  of  irrigation,  but  it  requires 
the  waste  of  the  major  portion  of  the  water  supply  in  normal 
years,  and  also  depends  upon  the  extremely  long  narrow  reser- 
voir, in  which  a  swiftly  flowing  stream  is  very  effective  in  cut- 
ting out  the  deposited  sediment.  The  variations  of  flow  of  the 
Nile  are,  moreover,  so  regular  that  a  predetermined  program  is 
possible,  which  would  be  utterly  impossible  upon  many  streams. 


REMOVAL  OF  SILT  FROM  RESERVOIRS  377 

This  combination  of  conditions  is  so  rare  that  the  solution 
adopted  has  little  application  to  most  cases,  and  presents  no 
general  solution  for  the  problem  in  hand. 

According  to  Table  XXXVI,  waters  of  the  Rio  Grande 
during  the  16  years  carried  if  per  cent  of  their  volume  of 
sediment  on  an  average.  The  detailed  observations  from  which 
this  summary  was  compiled  show  several  monthly  averages 
in  excess  of  10  per  cent,  and  in  general  the  percentage  fluctuated 
widely,  but  the  heaviest  percentages  are  found  in  the  four 
months  of  July,  August,  September  and  October,  and  especially 
August  and  September.  These  are  the  months  when  the  sudden 
torrential  rains  occur,  and  this  accounts  for  the  large  percentage 
of  sediment  in  those  months;  but  a  greater  portion  of  the  water 
is  discharged  in  April,  May  and  June,  while  the  snows  in  the 
mountains  are  melting,  and  though  the  percentage  of  sediment 
is  less  in  those  months,  the  total  quantity  is  often  greater, 
due  to  the  greater  quantity  of  water  flowing.  The  flow  in  the 
late  summer  is  very  unreliable,  and  it  is  necessary  to  meet  irriga- 
tion needs  by  storage  to  be  drawn  upon  at  that  time,  and  it  is 
therefore  impracticable  to  apply  the  methods  in  use  on  the  Nile, 
of  allowing  the  muddiest  water  to  flow  through  the  sluice  gates 
unchecked  by  the  reservoir.  That  method  is  also  impracticable 
for  the  further  reason  that  usually  all  the  water  is  needed  for 
irrigation,  and  must  be  stored  for  that  use. 

The  figures  show  an  accumulation  of  sediment  so  rapid  that 
unless  we  can  provide  some  means  of  disposing  of  it  and  of 
preserving  the  storage  capacity,  it  would  be  unwise  to  construct 
the  reservoir  and  build  the  homes  that  must  depend  upon  it, 
as  without  reliable  storage  they  must  be  abandoned. 

The  method  proposed  as  feasible  for  solving  this  problem 
on  the  Rio  Grande  is  applicable  to  many  other  streams,  and  a 
description  of  it  may  therefore  be  of  value  here.  It  is  recognized 
that  to  excavate  the  mud  from  the  reservoir  and  transport  it  to 
locations  outside  of  the  reservoir  by  ordinary  mechanical  methods 
would  be  very  expensive,  and  at  present  values  prohibitive. 
Even  if  it  could  be  accomplished  at  a  price  of  5  cents  per  cubic 
yard,  that  would  amount  to  about  $80  per  acre-foot,  whereas 


378  SEDIMENTATION  OF  RESERVOIRS 

the  cost  of  constructing  the  reservoir  was  about  $2  per  acre- 
foot,  and  an  enlargement  of  50  per  cent  can  probably  be  acccom- 
plished  at  about  the  same  rate. 

Therefore,  as  a  first  step  in  the  solution  of  the  silt  problem 
it  was  decided  to  construct  a  reservoir  of  nearly  twice  the  capac- 
ity absolutely  needed  to  control  the  flow  of  the  river,  so  that 
the  accumulations  of  sediment  will  not  seriously  encroach  upon 
the  necessary  storage  capacity  for  a  period  of  perhaps  40  to  50 
years.  At  that  time  the  works  will  have  been  long  paid  for, 
and  the  development  of  the  valley  will  be  such  that  an  enlarge- 
ment can  easily  be  made  which  will  furnish  storage  capacity 
sufficient  for  another  period  of  40  or  50  years.  The  reservoir 
thus  formed  will  be  over  50  miles  long,  and  will  not  be  very 
wide  at  any  point. 

On  the  headwaters  of  the  stream  and  its  tributaries  are 
several  smaller  reservoir  sites,  capable  of  development  to  the 
amount  of  several  hundred  thousand  acre-feet  at  moderate 
cost,  which  are  fed  by  melting  snows  and  will  fill  with  water 
carrying  very  little  sediment.  Whenever  the  reservoir  at 
Elephant  Butte  is  so  far  filled  with  mud  that  additional  storage 
is  needed,  one  or  more  of  the  mountain  reservoirs  can  be  built, 
and  the  necessary  storage  capacity  thus  provided. 

In  the  management  of  the  storage  works  it  would  be  the  policy 
to  hold  the  mountain  reservoir  full  of  water  as  long  as  possible, 
and  draw  on  the  lower  reservoir  for  needed  water  as  long  as 
any  water  remains  there  to  be  drawn.  When  the  lower  reservoir 
becomes  empty,  the  natural  flow  of  the  river,  reinforced  if 
required,  by  water  from  the  upper  reservoir,  would  flow  through 
the  sea  of  mud  accumulated  in  the  lower  reservoir,  and  cut  a 
channel  therein,  carrying  the  mud  thus  eroded  out  of  the 
reservoir  through  the  open  gates  as  the  water  is  needed  for 
irrigation.  Such  a  channel  extending  50  miles  through  the 
axis  of  the  reservoir  varying  in  depth  from  240  feet  at  the  dam 
to  zero  at  the  head  of  the  reservoir,  and  having  a  bottom  width 
of  250  feet,  and  side  slopes  of  3  to  i  would  itself  have  a  volume 
of  over  500,000  acre-feet.  All  the  water  flowing  through  the 
reservoir,  both  natural  flow  and  stored,  would  carry  from  10 


REMOVAL   OF   SILT   FROM   RESERVOIRS  379 

to  15  per  cent  of  its  volume  of  mud  until  such  a  channel  was 
cut,  and  nearly  as  much  for  a  long  time  after,  by  cutting  the 
banks  of  the  channel,  and  because  of  their  natural  tendency 
to  slide  and  to  slough. 

In  this  way,  an  equilibrium  could  be  established,  by  which 
the  amount  of  sediment  flowing  in  annually  would  be  offset 
by  the  average  amount  annually  discharged  as  above.  Just 
how  much  mountain  storage  would  be  necessary  to  accomplish 
this  could  be  established  only  by  experience,  but  until  such 
equilibrium  is  established  the  needs  of  storage  would  be  supplied 
by  building  reservoirs,  which  is  cheaper  than  mechanical  removal 
of  silt,  provided  good  reservoir  sites  exist,  as  they  do  in  the  basin 
of  the  Rio  Grande. 

It  will  be  seen  that  the  application  of  such  a  remedy  depends 
upon  the  topographic  and  hydrographic  characteristics  of  the 
drainage  basin,  including  the  shape  of  the  reservoir,  a  long 
narrow  and  deep  reservoir  being  most  favorable.  These  con- 
ditions would  not  be  found  in  every  case,  and  each  problem 
would  require  special  consideration. 

A  method  of  handling  the  silt  in  the  Elephant  Butte  Reservoir 
proposed  by  W.  W.  Follett,  is  as  follows: 

About  halfway  between  the  dam  and  the  head  of  the  reservoir, 
in  a  gorge  that  occurs  at  that  point,  it  was  proposed  to  build  a 
dam  40  or  50  feet  high,  forming  a  small  reservoir  within  the 
main  large  reservoir.  On  this  dam  provide  a  gate  tower,  extend- 
ing above  the  flow  line  of  the  reservoir.  The  gates  controlled 
from  this  tower  were  to  open  into  a  conduit  through  this  small 
dam,  which  would  pass  on  down  the  valley  as  a  large  pipe,  to  and 
through  the  main  reservoir  dam.  This  conduit  was  to  be  used 
to  draw  water  from  the  reservoir  whenever  possible. 

During  low  stages  of  the  main  reservoir  the  small  reservoir 
formed  by  the  small  dam  would  receive  the  water  of  the  river, 
and  much  of  the  sediment  would  be  deposited  therein  before 
the  water  passed  over  its  spillway  into  the  main  reservoir  below. 
At  such  times  as  the  small  reservoir  was  low,  the  turbid  natural 
flow  of  the  river  would  pass  through  the  conduit,  cutting  out  any 
silt  deposited  in  the  small  reservoir,  carry  its  load  of  fertile 


380  SEDIMENTATION   OF   RESERVOIRS 

sediment  to  the  irrigated  lands,  and  any  additional  water 
required  would  be  drawn  from  the  main  reservoir. 

This  provision  would  surely  have  provided  muddy  water  for 
irrigation  much  of  the  time,  instead  of  the  clear  water  now 
uniformly  furnished,  and  while  this  would  not  have  prevented 
the  encroachment  of  sedimentation  upon  the  storage  room,  it 
would  have  retarded  it.  Its  greatest  recommendation,  however, 
is  that  it  would  have 'preserved  the  fertilizing  qualities  of  the 
irrigation  water  and  thereby  increased  the  fertility  of  the  lands. 

This  plan  was  carefully  considered  by  a  board  of  engineers 
and  rejected  mainly  on  account  of  its  cost. 

REFERENCES  FOR  CHAPTERS  XV  AND  XVI 

STRANGE,  W.  L.  Indian  Storage  Reservoirs.  Spon  &  Chamberlain,  New  York. 
Report  of  Special  Committee  on  Flood  Prevention.  Trans.  Am.  Soc.  C.  E..  vol.  81, 

p.  1218. 
DAVIS,  ARTHUR  P.     Irrigation  Works  Constructed  by  the  United  States.     John 

Wiley  &  Sons,  New  York. 
SCHUYLER,  J.  D.     Reservoirs  for  Irrigation,  Water  Power  and  Domestic  Water 

Supply.     John  Wiley  &  Sons,  New  York. 

FLINX,  A.  D.     Rainfall,  Runoff  and  Development  of  Croton  Watershed.     Engi- 
neering News,  Feb.  6,  1908. 
DAVIS,  ARTHUR  P.     Water  Storage  on  Salt  River.     W.  S.  P.  73,  U.  S.  Geological 

Survey. 
LIPPINCOTT,  J.  B.     Water  Storage  on  Gila  River.     W.  S.  P.  33,  U.  S.  Geological 

Survey. 

FOLLETT,  W.  W.     Silt  in  Rio  Grande.     Engineering  News,  Jan.  15,  1914. 
HUGHES,  D.  E.     San  Carlos  Irrigation  Project.     House  Doc.  791,  63d  Congress, 

2d  Session. 
Davis,  Arthur  P.,  Report  on  Hydrography  of  Nicaragua,  1899. 


CHAPTER  XVII 
DAMS 

A  DAM  is  a  structure  placed  across  a  stream  or  gap  to  obstruct 
or  confine  water.  When  designed  to  permit  water  to  flow  over 
the  top,  it  is  called  a  weir.  In  such  a  case  it  must  be  built 
of  such  material  as  will  resist  a  tendency  to  wash  away  by  the 
flow  of  water.  This  may  be  either  masonry,  steel,  or  some  form 
of  wood. 

i.  Conditions  of  Safety. — All  dams,  of  whatever  magnitude 
or  type,  must  fulfill  certain  essential  conditions  for  safety. 

1.  They  must  have  practically  impervious  foundations  and 
abutments  sufficiently  stable  to  sustain  the  stresses  to  which 
they  will  be  submitted. 

2.  They  must  be  safe  against  sliding  either  on  foundation 
or  on  any  internal  joint. 

3.  They  must  be  safe  against  overturning. 

4.  They   must  be  practically  impervious,  and   have  water- 
tight connections  with  their  foundations  and  abutments. 

With  respect  to  their  functions,  dams  may  be  divided  into 
two  classes: 

1.  Diverson dams. 

2.  Storage  dams. 

A  diversion  dam  is  one  intended  only  for  raising  the  surface 
of  the  water  to  such  height  as  required  for  diverting  the  flow 
of  the  stream  into  a  canal  or  penstock,  for  power,  irrigation  or 
other  purposes.  The  great  majority  of  them  are  very  low, 
raising  the  water  only  a  few  feet,  and  intended  mainly  to  pro- 
vide a  permanent  sill  or  crest  at  the  proper  elevation  instead 
of  a  shifting,  fluctuating  channel.  Some  diversion  dams,  how- 
ever, are  as  high  as  200  feet,  and  these  are  often  used  also  partially 
for  storage  purposes. 

381 


382  DAMS 

Storage  dams  are  those  intended  to  form  reservoirs  to  store 
water  at  times  when  it  is  flowing  at  greater  volume  than  needed 
for  use,  and  to  hold  it  until  so  required.  Most  of  the  high  dams 
in  existence  are  intended  for  storage  purposes,  and  in  general 
they  are  built  higher  than  those  intended  only  for  diversion. 

2.  Diversion  Dams  or  Weirs. — Most  dams  intended  only  for 
diversion  purposes  are  of  the  weir  or  overfall  type,  designed  to 
permit  water  to  flow  over  the  top,  on  account  of  the  expense 
of  providing  safe  means  of  flow  elsewhere  for  the  floods.  For 
such  use  they  are  generally  built  of  wood  or  concrete  so  as  to 
resist  the  erosion  of  the  flowing  water. 

a.  Timber  Dams. — The  earliest  dams  were  built  by  beavers, 
and  were  composed  of  small  logs  and  brush.  These  have  been 
improved  upon  by  man,  by  adding  large  rocks  and  rude  piling 
to  hold  the  brush  in  place.  Such  rude  dams  were  general  in 
the  early  stages  of  irrigation,  and  were  employed  even  in  fairly 
large  streams,  not  to  raise  the  water,  but  to  divert  it  into  a 
canal  built  at  about  the  same  elevation  as  the  river  bed.  Such 
dams  were  often  breached  and  sometimes  entirely  destroyed 
by  floods  in  the  stream,  thus  depriving  the  canal  of  water  after 
the  subsidence  of  the  flood  until  it  could  be  replaced,  to  be 
again  destroyed  perhaps  after  a  short  time. 

One  of  the  earliest  types  of  such  structures  was  the  so-called 
"  burro  "  dam.  This  consisted  of  a  series  of  forked  stakes 
driven  into  the  sand  of  the  river  bed  at  intervals  of  6  or  8  feet 
across  the  stream,  inclined  slightly  upstream.  These  stakes  were 
as  large  as  could  be  driven  firmly  by  hand,  and  poles  were  placed 
in  the  crotches  of  the  stakes,  and  lashed  firmly  to  them,  thus 
forming  a  one-pole  fence  across  the  river,  3  or  4  feet  high.  Brush 
was  leaned  against  this  fence  from  the  upstream  side,  lashed  to 
the  fence,  and  rock  piled  upon  the  brush  ends  where  they  lay 
upon  the  river  bed ;  earth  was  dumped  on  the  rock  to  make  it 
tight.  Larger  rock  was  sometimes  placed  as  a  pavement  on  the 
downstream  side  of  this  rude  dam,  to  resist  the  erosion  of  the 
falling  water. 

Improvements  on  this  form  of  dam  by  the  use  of  heavier 
piling  driven  by  machinery  and  the  use  of  larger  rock  constituted 


DIVERSION  DAMS  OR  WEIRS 


383 


384  DAMS 

the  essential  features  of  most  of  these  temporary  structures 
which  were  cheap,  but  very  precarious.  They  could  be  built 
only  when  the  river  was  low,  and  often  caused  partial  or  total 
loss  of  crops  by  going  out  when  most  needed.  When  sub- 
jected to  alternate  wet  and  dry  conditions,  wood  decays  rapidly. 

When  a  timber  dam  is  built  in  a  stream  which  is  subject  to 
great  fluctuations  of  head  and  perhaps  dry  at  times,  the  wood 
tends  to  decay,  and  it  is  good  practice  to  combine  timber  and 
concrete  construction  in  such  cases.  The  foundation,  apron 
and  other  parts  which  will  be  perpetually  wet  may  be  built 
of  wood,  and  be  considered  permanent,  while  those  parts  which 
may  be  dry  at  times,  the  superstructure  and  abutments,  are 
built  of  concrete. 

A  form  of  low  timber  diversion  dam  sometimes  built  con- 
sists of  a  plank  platform  held  in  place  by  a  series  of  piling  driven 
into  the  river  bed.  On  this  foundation  timber  frames  are 
erected  at  close  intervals  in  the  form  of  the  letter  A.  These  are 
firmly  bolted  to  the  foundation,  and  the  upstream  legs  of  the 
frames  closed  with  heavy  planking.  The  water  is  allowed  to 
flow  over  the  top  of  this  diaphragm  and  fall  upon  the  plant 
platform  below,  which  is  placed  a  little  below  the  natural  river 
bed,  and  is  perpetually  submerged.  Such  dams  have  been  used 
successfully  in  many  cases. 

b.  Rectangular  Pile  Weirs. — These  have  been  employed 
in  wide  sandy  rivers  like  the  Platte,  in  Colorado.  They  consist 
of  a  double  row  of  piling  driven  into  the  river-bed,  the  two  rows 
being  about  6  feet  apart,  and  the  piles  about  3  feet  apart  between 
centers.  Between  these  is  driven  sheet  piling  to  prevent  the 
seepage  or  travel  of  water  through  the  barrier,  and  the  upper 
portion  of  the  structure  is  planked  so  as  to  form  a  rectangular 
wall  the  interior  of  which  is  filled  in  with  gravel,  sand,  etc.  Such 
walls  are  usually  low,  rarely  exceeding  8  feet  in  height,  and  after 
the  upper  side  is  backed  with  the  silt  deposited  from  the  stream 
they  form  substantial  barriers  which  may  last  a  few  years. 
Such  structures  cannot  be  employed  where  the  flood  height 
is  great,  as  they  would  soon  be  undermined  unless  substantial 
aprons  were  constructed. 


DIVERSION  DAMS  OR  WEIRS 


385 


egulator 


CROSS  SECTION   OF  WEIR. 

FIG.  179. — Folsom  Canal  Plan  and  Cross-section  of  Weir. 


386  DAMS 

c.  Open  and  Closed  Weirs. — A  closed  weir  is  one  in  which 
the  barrier  which  it  forms  is  solid  across  nearly  the  entire  width 
of  the  channel,  the  flood  waters  passing  over  its  crest.  Such 
weirs  have  usually  a  short  open  portion  in  front  of  the  regulator 
known  as  the  "  scouring-sluice,"  the  object  of  which  is  to  main- 
tain a  swift  current  past  the  regulator  entrance,  and  thus  prevent 
the  deposit  of  silt  at  that  point.  An  open  weir  is  one  in  which 
scouring-sluices  or  openings  are  provided  throughout  a  large  por- 
tion of  its  length  and  for  the  full  height  of  the  weir. 

The  advantage  of  the  closed  weir  is  that  it  is  self-acting,  and 
if  well  designed  and  constructed  requires  little  expense  for  repairs 
or  maintenance,  but  it  interferes  with  the  normal  regimen 
of  the  river,  causing  deposit  of  silt  and  perhaps  changing  the 
channel  of  the  stream.  Open  or  scouring-sluice  weirs  interfere 
little  with  the  normal  action  of  the  stream,  and  the  scour  pro- 
duced by  opening  the  gates  prevents  the  deposit  of  silt. 

The  closed  weir  consists  of  an  apron  properly  founded  and 
carried  across  the  entire  width  of  the  river  flush  with  the  level  of 
its  bed,  and  protected  from  erosive  action  by  curtain-walls  up- 
and  downstream.  On  a  portion  of  this  is  constructed  the  super- 
structure, which  may  consist  of  a  solid  wall  or  in  part  of  upright 
piers,  the  interstices  between  which  are  closed  by  some  temporary 
arrangement.  During  floods  the  water  backed  against  the 
weir  acts  as  a  water  cushion  to  protect  the  apron,  and  as  the 
flood  rises  the  height  of  the  fall  over  the  weir  crest  diminishes,  so 
that  with  a  flood  of  16  feet  over  an  ordinary  weir  its  effect  as  an 
obstruction  wholly  disappears.  A  rapidly  rising  flood  is  more 
dangerous  than  a  slowly  rising  flood,  not  only  because  of  its 
greater  velocity,  but  because  it  causes  a  greater  head  or  fall 
over  the  weir  as  the  water  has  not  had  time  to  back  up  below 
and  form  a  water-cushion.  For  the  same  reasons  a  falling  or 
diminishing  flood  is  less  dangerous  than  a  rising  flood. 

An  open  weir  consists  of  a  series  of  piers  of  wood,  iron,  or 
masonry,  set  at  regular  intervals  across  the  stream  bed  and  rest- 
ing on  a  masonry  or  wooden  floor.  This  floor  is  carried  across 
the  channel  flush  with  the  river  bed  or  lower,  and  is  protected 
from  erosive  action  by  curtain-walls  up-  and  downstream.  The 


I  /Cx  J^ 


CALIFORNIA 


Colorado  liii-( 


SCALE  OF  FEET 

0  200  400  GOO 


150  Feef 


Concrete';   jj  '         -0 
6"Wood  Sheet  Piling-—^pj  i £ 


Concrete 


-67'6- 


1'il 


MAXIMUM 
FIG.  i  So.— Plan  and  Sect 


3000  3500 

ORINGS  ON   LINE  A 


5000 


141.0  Kiev.  Low  Water  1004 


'ION  ON  C-D 
Laguna  Dam,  Colorado  River. 


To  face  page  386. 


DIVERSION  DAMS  OR   WEIRS 


387 


pieis  are  grooved  for  the  recep- 
tion of  flashboards  or  gates  so 
that  by  raising  or  lowering 
these  the  height  of  the  river 
can  be  controlled.  The  distance 
between  the  piers  varies  be- 
tween 3  and  10  feet,  according 
to  the  style  of  gate  used.  If 
the  river  is  subject  to  sudden 
floods  these  gates  may  be  so 
constructed  as  to  drop  auto- 
matically when  the  water  rises 
to  a  sufficient  height  to  top 
them.  It  is  sometimes  neces- 
sary to  construct  open  weirs  in 
such  manner  that  they  shall  offer 
the  least  obstruction  to  the 
waterway  of  the  stream.  This 
is  necessary  in  weirs  like  the 
Barage  du  Nil,  below  Cairo, 
Egypt,  or  in  some  of  the  weirs 
on  the  Seine,  in  France,  in  order 
that  in  time  of  flood  the  height 
of  water  may  not  be  appreci- 
ably increased  above  the  fixed 
diversion  height.  Should  the 
height  be  increased  in  such 
cases  the  water  would  back  up, 
flooding  and  destroying  valuable 
property  in  the  cities  above. 
Under  such  circumstances  open 
weirs  are  sometimes  so  con- 
structed that  they  can  be 
entirely  removed,  piers  and  all, 
leaving  absolutely  no  obstruc- 
tion to  the  channel  of  the 
stream,  and  in  fact  increasing 


388  DAMS 

its  discharging  capacity,  owing  to  the  smoothness  which  they 
give  to  its  bed  and  banks. 

d.  Flashboard  Weirs. — A  form  of  cheap  open  weir  which 
has  been  commonly  constructed  in  the  West  is  the  open  wooden 
frame  and  flashboard  weir.  This  type  of  structure  is  used  only 
on  such  rivers  as  have  unstable  beds  and  banks,  where  any 
obstruction  to  the  ordinary  regimen  of  the  stream  would  cause 
a  change  in  its  channel.  It  consists  wholly  or  in  part  of  a  founda- 
tion of  piling  driven  into  the  river  bed,  upon  which  is  built  an 
open  framework  closed  by  horizontal  planks  let  into  slots  in  the 
piers.  These  weirs  are  constructed  of  wood,  and  are  temporary 
in  character,  their  chief  recommendation  being  the  cheapness 
with  which  they  can  be  built  in  rivers  the  beds  of 
which  are  composed  of  a  considerable  depth  of  silt  or  light 
soil. 

A  more  common  type  of  frame  or  flashboard  weir  is  that 
employed  on  the  Kern  River  in  California.  (Fig.  182.)  An 
example  of  this  is  the  weir  at  the  head  of  the  Galloway  canal 
(Fig.  183),  which  consists  of  100  bays,  each  separated  by  a  simple 
open  triangular  framework  of  wood  founded  on  piles,  the  width 
of  each  opening  or  bay  being  4  feet.  Two  and  one-half  feet  below 
the  bed  of  the  stream  is  a  floor,  with  walls  about  2  feet  in  height, 
forming  compartments  filled  with  sand  on  which  the  waters  fall. 
This  apron  is  carried  up-  and  downstream  for  a  distance  of  about 
10  feet  in  each  direction.  The  weir  proper  is  formed  of  frames  or 
trusses  of  6  by  6  inch  timber,  placed  transversely  4  feet  apart. 
These  frames  consist  of  two  pieces,  the  upstream  piece  being  1 5 
feet  2  inches  long  and  set  at  an  angle  of  38  degrees,  while  the  other 
supports  it  at  right  angles  and  is  9  feet  4  inches  long.  The  lower 
ends  of  these  rafters  thrust  against  two  pieces  of  6  by  2  inch 
timber  running  the  whole  length  of  the  weir  and  nailed  to  the 
flooring.  These  frames  are  supported  directly  on  anchor  piles, 
one  at  each  end  joiced  into  the  framing.  These  trusses  are 
kept  in  vertical  position  by  means  of  a  footboard  running  trans- 
versely the  entire  width  of  the  stream.  On  the  upstream  face 
of  the  trusses  planks  or  flashboards  which  slide  between  grooves 
formed  by  nailing  face-boards  on  the  trusses  are  laid  on  to  the 


DIVERSION  DAMS  OR   WEIRS 


389 


390 


DAMS 


required  height.     This  weir  is  10  feet  in  height  above  the  wooden 
floor,  which  is  flush  with  the  river  bed. 

e.  Indian  Type  Weirs. — A  substantial  form  of  weir  is  that 
generally  constructed  on  Indian  rivers,  where  the  banks  and 
bed  are  of  sand,  gravel,  or  other  unstable  material.  These  weirs 
generally  rest  on  shallow  foundations  of  masonry,  in  such  manner 
that  they  practically  float  on  the  sandy  beds  of  the  streams. 


FIG.  183. — Cross-section  of  Open  Weir.  Galloway  Canal. 


The  foundation  of  such  a  weir  is  generally  of  one  or  more  rows 
of  wells  sunk  to  a  depth  of  from  6  to  10  feet  in  the  bed  of  the 
river,  the  wells  and  the  spaces  between  the  wells  being  filled 
in  with  concrete,  thus  forming  a  masonry  wall  across  the  channel. 
A  well  or  block  is  a  cylindrical  or  rectangular  hollow  brick 
structure,  which  is  built  upon  a  hard  cutting  edge  like  a  caisson, 
and  from  the  interior  of  which  the  sand  is  excavated  as  it  sinks. 
After  it  has  reached  a  suitable  depth  it  is  filled  with  concrete, 
depending  partly  for  its  stability  on  the  friction  against  its  sides. 
This  form  of  construction  is  illustrated  in  Fig.  184. 


DIVERSION  DAMS  OR   WEIRS 


391 


NARORA    WEIR-  LOWER   GANGES  CANAL 
length  7260  metres 


OKHLA  WEIR -AGRA    CANAL., 
Length  743  metres 


DEHREE   WEJR-SOANE  CANAL 
length  5825  metres 


ITT. 


6EZWARA    WEIR  -  KISTNA  CANAL. 

length  1150  metres. 


60DIVERY        WEIR, 
length  6274  metres. 


FIG.  184. — Cross-sections  of  Indian  Weirs. 


392 


DAMS 


f.  Automatic  Shutters  and  Gates. — The  use  of  flashboards 
or  any  similar  permanent  obstruction  in  a  wasteway  in  order  to 
increase  the  storage  capacity  of  the  reservoir  is  to  be  discouraged. 
Such  obstructions  must  be  removed  at  the  time  of  great  floods 
or  else  these  will  top  the  dam,  which  depends  upon  the  attention 
of  watchmen,  who  may  be  absent  or  negligent.  Automatic 
shutters,  however,  have  been  used  with  considerable  success 
in  a  few  instances. 

One  of  the  most  desirable  forms  of  these  is  that  shown  in 
Fig.  185.  It  consists  of  a  row  of  upright  iron  shutters,  each 
1 8  feet  long  and  22  inches  high.  These  are  supported  by  ten- 
sion-rods hinged  to  the  crest  of  the  weir  on  the  upstream  side, 
and  to  the  upper  side  of  the  shutter  at  about  two-thirds  of 
the  distance  from  its  crest,  or,  in  other  words,  below  its  center 


FIG.  185. — Cross-section  of  Shutter  on  Soane  Weir,  India. 


of  pressure.  As  soon  as  the  water-level  approaches  the  top  of 
the  shutter  it  causes  its  lower  end  to  slide  inward  and  the  whole 
falls  flat  against  the  top  of  the  weir,  offering  no  obstruction  to 
the  passage  of  the  water. 

g.  Automatic  Drop-shutters. — The  shutters,  added  in  1901 
to  the  crest  of  the  Betwa  weir  at  Paricha,  India,  to  increase 
the  reservoir  capacity  may  be  taken  as  illustrative  of  the 
latest  Indian  practice  in  the  design  of  automatic  drop-shutters. 

The  shutters  are  each  6  feet  high  and  12  feet  long,  and  as 
the  length  of  the  weir  crest  is  3600  feet  there  are  300  such 
shutters.  They  are  made  entirely  of  steel,  consisting  of  }-inch 
plates  joined  along  their  middle  and  stiffened  both  longitudinally 
and  laterally  by  angle-iron  3^  by  2\  by  f  inch  (Fig.  186). 
To  the  flanges  of  the  vertical  stiff  eners  are  pivoted  if -inch 
tension-bars.  The  other  end  is  similarly  attached  to  anchor- 


DIVERSION  DAMS  OR  WEIRS 


393 


bolts  built  2  feet  into  the  masonry  crest  of  the  weir.  There  are 
four  such  tension-bars  to  each  1 2-foot  gate.  The  point  of 
attachment  of  the  tension-bar  and  shutter  is  so  designed  that 
the  gates  fall  automatically  with  a  given  depth  of  water  passing 


331.90 


P.O.  Concrete  \     D 

"Lime  Concrete 


>28.5 


5V 

OLD  WEIR  RUB.  MASONRY. 
12V-' 


\      M.S.  Plate    / 


ShoeJ*       ELEVATION. 

nTTllL  Jllililllii'v  TT 


/        M.S.  Plate 


T' 


L.I.  Stiffene 


M  Plate 


SECTION 


,L.I.  Stiffened 


>L.I.  Brace  3^'x  2&\  %" 


y 

Shoe 


M.S.  Plate  %" 
BOTTOM  PLAN. 


L.I.  Stiffener  3>*  x 


FIG.  1 86. — Automatic  Drop-shutter,  Betwa  Weir,  India. 

over  them,  thus  securing  safety  in  case  of  excessive  floods.  The 
bottom  of  each  gate  is  supplied  with  four  steel  shoes,  which  rest 
upon  sliding-plates  built  into  the  weir  crest,  thus  reducing 
the  frictional  resistance  when  the  gates  fall.  Wooden  baulks 
4  by  4  inches  are  fixed  to  the  ends  of  the  shutters,  which  have  a 


394  DAMS 

space  of  i  inch  separating  them,  which  is  caulked  when  the 
gates  are  raised. 

If  the  300  shutters  were  to  fall  together  the  shock  would 
unduly  strain  the  weir  and  tne  flood  volume  submerge  the  river- 
banks  below.  Hence  the  attachment  of  the  tension-bars  has 
been  so  arranged  that  each  third  gate  falls  under  different  depths 
of  water.  The  first  third  fall  with  a  depth  over  top  of  2  feet, 
the  next  with  3  feet,  and  the  last  with  4  feet.  Thus  after  the 
first  third  fall  the  released  water  reduces  the  flood  depth,  and 
the  latter  must  increase  considerably  to  top  the  second  third, 
and  so  on  for  the  last  third. 

These  shutters  were  subjected  to  an  unusual  test,  immediately 
after  completion,  in  the  form  of  an  extraordinary  flood  which 
passed  over  the  weir  crest  to  the  height  of  16.4  feet,  when  it  had 
been  designed  to  withstand  a  previous  known  flood  height  of 
only  6.5  feet.  Fortunately  the  shutters  worked  success- 
fully and  neither  weir  nor  shutters  sustained  material 
injury. 

h.  French  Type. — The  weirs  on  the  River  Seine  in  France 
differ  materially  from  the  Indian  weirs.  They  consist  of  a 
series  of  iron  frames  of  trapezoidal  cross-section,  somewhat 
similar  in  shape  to  the  frames  of  the  open  wooden  flashboard 
weirs  of  California.  On  these  frames  rest  a  temporary  footway, 
and  on  their  upper  side  is  placed  a  rolling  curtain  shutter  or 
gate  which  can  be  dropped  so  as  to  obstruct  the  passage  of  water 
across  the  entire  channelway  of  the  stream,  or  can  be  raised  to 
such  a  height  as  to  permit  the  water  to  flow  under  them-.  In 
times  of  flood  the  curtain  can  be  completely  raised  and  removed 
on  a  temporary  track  to  the  river  banks,  the  floor  and  track 
can  then  be  taken  up,  leaving  nothing  but  the  slight  iron  frames, 
which  scarcely  impede  the  discharge  of  the  river  and  permit 
abundant  passageway  of  the  floods  over,  around,  and  through 
them  (Fig.  188). 

i.  Roller  Dams. — A  movable  dam  invented  and  patented 
in  Germany,  consisting  of  steel  rollers,  capable  of  being  rolled 
up  an  incline  when  required  to  pass  floods,  has  been  used  in 
that  country  and  also  in  a  few  instances  in  the  United  States. 


DIVERSION  DAMS  OR   WEIRS 


395 


FIG.  187, — Falling  Sluice-gate,     Soane  Canal,  India. 


396 


DAMS 


The  largest  one  built  in  this  country  is  on  Grand  River,  about 
eight  miles  above  Palisade,  Colorado. 

In  the  diversion  of  Grand  River,  the  problem  presented 
was  to  raise  the  level  of  the  river  at  low  stages  sufficiently  to 
divert  1400  cubic  feet  of  water  per  second  into  the  head  of  the 
canal,  and  yet  at  high  water  to  pass  a  flow  of  50,000  cubic  feet 
of  water  per  second  without  raising  the  water  to  a  level  where 
it  would  endanger  the  roadbed  of  the  railroad  adjacent.  This 
required  a  movable  crest  upon  a  concrete  weir. 


FIG.  1 88. — View  of  Open  Weir  on  River  Seine,  France. 

The  dam  developed  is  a  concrete  base  of  ogee  section  with 
projecting  apron,  surmounted  by  a  series  of  seven  movable 
roller  dams,  six  of  which  are  70  feet  long  and  10.25  feet  high, 
over  the  dam  proper,  while  the  seventh  has  a  span  of  60  feet 
and  a  height  of  15.3  feet,  and  is  used  to  control  the  sluiceway. 
The  total  length  of  the  structure  is  536.5  feet.  When  the  rollers 
are  closed  at  low  water  it  raises  the  water  20  feet  above  the  bed 
of  the  river.  See  Fig.  190. 

The  canal  regulator  gates  are  parallel  to  the  river,  and  nearly 
on  a  line  with  the  natural  bank,  and  the  sluiceway  roller  closes 
upon  a  sill  5.1  feet  below  the  sills  of  the  other  rollers,  and  8.3 


DIVERSION  DAMS  OR   WEIRS 


397 


398 


DAMS 


DIVERSION  DAMS  OR   WEIRS 


399 


feet  below  the  sills  of  the  canal  gates,  so  that  gravel  will  be 
deposited  instead  of  passing  into  the  canal,  and  can  be  sluiced 
out  by  raising  the  6o-foot  roller,  and  thus  a  deep  settling  basin 


FIG.  191. — Section  through  Body  of  yo-foot  Roller  Dam,  Grand  River,  Colorado. 

can  be  maintained  in  front  of  the  gates,  to  prevent  the  river 
gravel  from  entering  the  canal. 

The  hoisting  apparatus  for  the  sluicing  roller  is  located  on 
the  right  abutment  of  the  dam,  which  serves  also  for  the  left 
abutment  of  the  headgate  structure.  The  other  six  rollers  are 


400 


DAMS 


operated  by  three  hoists  located  on  alternate  piers,  each  hoist 
serving  two  rollers.  These  piers  are  10  feet  wide,  and  the  other 
three  are  8.25  feet  wide.  A  steel  truss  bridge  spans  each  open- 
ing. Each  hoist  is  equipped  with  an  electric  motor  receiving 
current  from  a  gas  engine  in  the  gate  house  on  the  right  abutment 


. 

'   (thru,  c.  of  halt  circle) 

'      /^/Filler  plate #6"jc8*&  354 


»'«'3' 

Illllllllll 


FIG.  192. — Section  through  Driven  End  of  7o-foot  Roller. 

pier.     The  rollers  are  lifted  by  rolling  them  up  the  inclined  tops 
of  the  piers. 

The  advantages  of  this  type  of  movable  dam,  are  its  long  span, 
requiring  but  few  piers  to  obstruct  drift,  the  ease  and  speed 
with  which  it  can  be  opened,  and  the  tightness  of  closure,  per- 
mitting little  leakage. 


DIVERSION  DAMS  OR  WEIRS 


401 


j.  Crib  Dams. — A  type  of  dam  much  employed  in  early  days, 
and  still  frequently  built,  consists  of  a  series  of  cribs  built  of  logs 
firmly  bolted  or  pinned  together,  and  filled  with  large  and  small 
rock  to  give  weight  and  stability.  The  cribs  are  rectangular, 
from  12  to  1 6  feet  square,  and  longer  timbers  extend  from  one 
crib  to  the  next  to  bind  them  firmly  together.  A  floor  of  heavy 
timbers  is  provided  near  the  bottom  of  each  crib  for  holding  the 
rock.  The  bottom  of  each  crib  should  be  drift-bolted  to  the 
foundation  if  of  rock,  and  sunk  as  low  as  possible  into  any 
softer  foundation,  and  sheet  piling  may  be  added  to  stop  per- 
colation under  the  dam.  It  is  best  to  give  the  dam  a  slope  of  45 
degrees  or  flatter  on  the  upstream  face,  and  to  cover  this  with 


. 


FIG.  193. — Cross-section  of  Bear  River  Weir. 

planking  for  water  tightness.  The  lower  side  may  be  likewise 
sloped  and  covered  with  planks,  but  it  is  best  to  make  this  slope 
steep  at  top,  and  gradually  flatten  it  toward  the  bottom  to  give 
the  falling  water  gradually  a  horizontal  direction  as  it  leaves 
the  dam.  The  bottom  of  the  river  for  some  distance  below  the 
dam  should  be  protected  from  erosion  by  submerged  cribs 
covered  with  heavy  planks  or  sawn  timbers,  and  filled  with  the 
largest  available  rock. 

Where  a  crib  dam  is  of  considerable  height,  the  downstream 
slope  is  sometimes  made  in  a  series  of  steps  to  break  the  fall 
of  the  water  and  dissipate  the  greater  part  of  its  energy  before 
reaching  the  toe  of  the  dam. 


402 


DAMS 


k.  Submerged  Dams. — In  desert  regions,  it  frequently  happens 
that  small  streams  emerge  from  the  mountains  and  are  lost 
in  the  sands  and  gravels  of  the  desert  before  reaching  any 
larger  stream,  or  other  outlet.  In  times  of  flood  the  water  flows 


stjfl       « 


a  much  greater  distance  over  the  desert  than  normally,  and 
in  so  doing  forms  a  water  course  which  is  usually  dry  on  the 
surface  or  nearly  so.  Numerous  attempts  have  been  made 
to  bring  the  underflow  to  the  surface  by  sinking  concrete  or 
wooden  dams,  called  submerged  dams,  in  the  ground  across 


DIVERSION  DAMS  OR   WEIRS  403 

the  water  course.     These  have  at  times  collected  some  water, 
but  the  quantity  has  usually  been  disappointing. 

One  such  structure  is  the  dam  on  Pacoima  Creek  in  Cali- 
fornia, the  property  of  the  San  Fernando  Land  and  Water 
Company.  At  the  site  of  the  dam  the  sandstone  canyon  walls 
are  about  800  feet  apart  and  the  bed  rock  about  45  feet  below 
the  surface  of  the  gravel  bed  of  the  stream.  Through  this  a 


_^ 


FlG.  195. — View  of  San  Fernando  Submerged  Dam. 

trench  was  excavated  across  the  canyon  in  which  a  rubble 
masonry  wall  was  built,  its  base  being  about  3  feet  thick  and  its 
top  2  feet  reaching  2  or  3  feet  above  the  stream  bed.  On  the  line 
of  this  wall  are  two  large  gathering  wells,  and  on  its  upper  face 
pipes  are  laid  in  open  sections,  so  that  the  seepage  water  caught 
by  the  dam  might  enter  these  and  be  led  through  them  into 
the  wells,  from  which  it  is  drawn  off  for  purposes  of  irrigation. 
Above  the  dam  the  stream  bed  consists  of  several  hundred  acres 
of  gravel  12  to  20  feet  in  depth,  which  forms  a  natural  storage 
reservoir  of  1200  to  1500  acre-feet  capacity. 

A  somewhat  similar  submerged  dam  is  in  operation  at  King- 
man,  Ariz.,  for  providing  a  small  supply  to  the  town  and  railway. 


404  'DAMS 

A  masonry  wall  173  feet  long  on  top,  6  feet  wide  at  base;  and  2 
feet  wide  on  top  is  built  on  bed-rock  across  and  through  the 
gravel  bed  of  railroad  canyon.  A  6-inch  cast-iron  outlet  pipe 
through  the  dam,  12  feet  below  its  crest,  which  is  below  the 
level  of  the  canyon  bed,  leads  into  an  8-inch  standpipe  per- 
forated with  f-inch  holes  placed  J  inch  apart.  In  this  is  col- 
lected the  water  which  gathers  behind  the  dam  to  the  full 
height  of  its  crest. 

3.  Storage  Dams. — Storage  dams  may  be  classified  into  four 
general  groups  according  to  the  materials  of  which  they  are 
composed  as  follows: 

1.  Earth  dams  or  embankments. 

2.  Rock-filled  dams. 

3.  Steel  dams. 

4.  Masonry  dams. 

Numerous  modifications  and  combinations  of  the  above 
types  are  often  employed,  as  for  example,  a  combination  of  the 
earth  and  rock-fill  types,  of  which  this  chapter  treats. 

The  type  of  dam  to  be  constructed  at  any  given  site  is  deter- 
mined chiefly  upon  consideration  of  three  leading  elements 
which  are  usually  capable  of  interpretation  in  terms  of  cost. 

1.  Character  of  available  materials  for  construction. 

2.  Character  of  foundation  and  abutment. 

3.  Length  and  height  of  dam. 

It  often  happens  that  the  dam-site  is  in  a  rocky  canyon, 
where  there  is  not  available  within  reasonable  distance  a  suffi- 
cient quantity  of  material  suitable  for  an  earthen  dam,  and  the 
difficulty  of  making  a  tight  bond  between  the  rock  and  an  earth 
embankment,  furnishes  additional  reason  for  rejecting  this 
type. 

Where  the  dam-site  is  a  narrow  gorge  with  good  rock  founda- 
tion and  abutments  so  that  a  masonry  dam  of  light  section 
depending  on  arch  action  can  be  built,  this  type  is  usually  the 
cheapest,  and  commends  itself  to  the  general  public  for  its 
safety  and  stability  if  well  built. 

If  the  gorge  is  more  than  600  feet  wide  at  the  top  of  the  pro- 
posed, dam,  so  that  little  advantage  can  be  secured  from  arch 


STORAGE  DAMS  405 

action,   the*  rock-fill  type  may  be  worthy  of  consideration  in 
comparison  with  a  masonry  dam. 

Where  the  dam  is  to  be  of  considerable  length,  and  con- 
ditions are  at  ail  favorable  for  an  earthen  dam,  this  type  is 
generally  cheapest,  can  be  made  perfectly  safe,  and  its  choice  is 
therefore  advisable  unless  it  is  to  be  very  high,  in  which  case 
masonry  should  also  be  considered  if  a  foundation  of  good  rock 
is  available. 

a.  Earthen  Dams  or  Embankments. — The   essential  features 
of  a  serviceable  earthen  dam  are  five : 

1.  That  it  is  protected  by  an  ample  spillway,  from  the  flow 
of  water  over  any  portion. 

2.  That  the  water  slope  or  the  center,  or  both,  be  practically 
impervious  to  water. 

3.  That  the  foundation  and  abutments  be  practically  imper- 
vious, and  connected  with  the  dam  by  a  water-tight  bond. 

4.  That  the  water  slope  be  protected  from  wave  action  by 
paving  or  riprap. 

5.  That  both  slopes  be  sufficiently  flat  to  insure  the  class  of 
material  used  against  sloughing. 

There  are  three  general  types  of  earthen  dams,  classified  with 
reference  to  the  portion  made  impervious: 

1.  Dams  having  a  central  core  of  puddled  earth,  or  a  central 
wall  of  masonry. 

2.  Dams  having  the  water  face  and  center  built  of  selected 
material  made   nearly  impervious,   and  coarser  material  used 
on  lower  face. 

3.  Dams  built  in  layers  of  homogeneous  material  throughout, 
which  must  of  course  be  nearly  impervious. 

It  must  be  remembered  that  all  earthen  masses,  and  most 
rock  and  concrete  is  capable  of  absorbing  and  transmitting  some 
water  if  sufficient  pressure  be  applied,  and  so  when  we  speak  of 
impervious  materials  in  earthen  dams,  we  speak  relatively. 

b.  Foundation. — No  feature  of  the  site  for  an  earthen  dam  is 
more  important  than  the  foundation,  and  this  should  be  examined 
with  great  care.     If  it  consists  of  alluvial  material  deposited 
by  water,  it  is  likely  to  contain  pervious  strata  of  sand  or  gravel, 


406 


DAMS 


STORAGE  DAMS  407 

and  these  if  left  undisturbed  will  produce  leakage  under  the 
dam,  which  under  the  head  of  water  in  the  reservoir  might 
attain  destructive  velocities  and  cause  disaster.  Free  percola- 
tion must  be  entirely  prevented,  and  all  percolation  must  be 
made  so  slow  and  devious  that  it  will  be  inert,  and  without 
danger  of  destructive  erosion.  In  general  it  is  necessary  to 
provide  a  wide  cut-off  channel  or  core  wall,  carried  down  to 
rock,  or  to  a  thick  bed  of  relatively  impervious  material,  through 
which  such  percolation  as  occurs  will  be  very  slow.  The  best 
foundation  for  an  earthen  dam  is  a  thick  bed  of  impervious  clay 
mixed  with  a  large  proportion  of  sand  and  gravel  thus  combining 
water- tightness  with  stability.  A  foundation  of  fine  sand  is 
not  permissible  unless  it  contains  some  clay  or  impalpable 
silt.  In  the  case  of  any  foundation  which  will  permit  some 
percolation,  there  is  an  advantage  in  making  the  path  which 
the  water  must  follow  in  order  to  reach  a  free  escape,  as  long  as 
possible,  which  may  be  secured  by  spreading  the  base  of  the  dam 
if  this  is  made  of  impervious  material,  thus  confining  the  per- 
colating waters  for  a  greater  distance  before  they  can  escape. 
It  was  upon  this  theory  that  the  Gatun  Dam  on  the  Canal 
Zone  was  given  very  flat  slopes,  and  a  very  wide  base.  If  an 
earthen  dam  is  to  be  connected  with  rock  either  in  its  founda- 
tions or  abutments,  it  should  be  by  means  of  one  or  more  walls 
of  concrete,  cemented  tightly  to  the  rock,  and  extending  several 
feet  into  the  earthen  embankment.  The  earth  around  these 
concrete  cut-off  walls  should  be  carefully  selected,  puddled  and 
rammed,  so  as  to  give  the  tightest  possible  connection. 

In  preparing  the  foundation  of  an  earthen  dam  for  the 
embankment,  the  surface  soil  should  be  removed  from  the 
foundation  to  a  depth  sufficient  to  remove  all  coarse  vegetation, 
and  the  entire  foundation  scored  by  deep  furrows  running  longi- 
tudinally of  the  dam,  so  as  to  form  a  good  bond  with  the  embank- 
ment material. 

If  pervious  strata  of  sand  or  gravel  occur  below  the  surface, 
one  or  more  trenches  should  be  carried  down  through  such 
strata  for  the  entire  length  of  the  foundation,  and  refilled  with 
selected  material  carefully  rammed  or  puddled  in  place. 


408 


DAMS 


c.  Springs  in  Foundations. — It  sometimes  happens  that  one 
or  more  springs  occur  at  the  site  where  it  is  desired  to  build 
an  earthen  dam.  This  is  very  undesirable,  and  if  possible  a 
site  should  be  selected  which  is  free  from  this  menace.  Where 


TRUCKEE-CARSON 
PROJECT  NEVADA 

LAHONTAN   DAM 
GENERAL  PLAN   OF  DAM 


FIG.  197. — Plan  of  Lahontan  Dam,  Carson  River,  Nevada. 

this  is  not  possible,  the  utmost  precaution  must  be  taken  to 
prevent  the  spring  from  endangering  the  structure.  If  possible 
the  spring  should  be  followed  to  its  point  of  emergence  from  the 
rock.  If  the  rock  is  hard  and  firm,  it  may  be  possible  to  seal 


STORAGE  DAMS  409 

the  spring  with  a  mass  of  concrete.  If  this  is  done,  careful 
examination  should  be  made  to  determine  whether  the  spring 
has  broken  out  at  some  other  point.  If  the  spring  does  not  flow 
from  rock,  it  may  be  followed  to  relatively  firm  material,  and 
there  confined  into  a  pipe  and  led  away  and  discharged  at  a 
distance  from  the  dam,  due  precaution  being  taken  against 
the  percolation  of  water  through  the  bank  along  the  pipe.  Or 
still  better  the  pipe  may  be  carried  upward  and  sloped  upstream 
if  necessary,  until  its  top  is  above  the  flow  line  of  the  reservoir, 
and  the  water  allowed  to  flow  out  at  the  top  if  it  will,  and  fall 
into  the  reservoir. 

If  the  springs  are  small,  it  may  be  possible  to  smother  them 
by  puddled  material,  but  this  should  be  done  with  caution, 
and  careful  examination  made  to  detect  their  escape  at  other 
points.  This  method  should  never  be  attempted,  however, 
unless  excellent  and  abundant  puddle  material  is  used  for  the 
purpose,  and  the  spot  is  buried  under  a  great  mass  of  which  the 
weight  and  character  is  a  guarantee  against  any  escape  of  the 
water  or  any  portion  of  it.  This  process  should  never  be  applied 
to  springs  below  the  center  line  of  the  dam,  where  they  might 
saturate  the  lower  portion  of  the  dam  and  cause  a  tendency  to 
slough.  The  handling  of  springs  in  foundations  is  a  very  impor- 
tant and  delicate  problem  requiring  experience  and  mature 
judgment,  as  an  error  in  the  solution  of  this  problem  may  lead 
to  serious  consequences. 

d.  Safe  Slopes  for  Earthen  Dams. — One  of  the  strongest 
tendencies  to  failure  of  an  earthen  dam  is  the  saturation  of  its 
mass  with  water,  with  a  consequent  tendency  to  neutralize  its 
cohesion  and  to  cause  parts  of  it  to  become  of  a  semi-liquid 
nature,  so  that  it  will  slide  or  slough.  This  is  one  great  reason 
for  the  importance  of  making  the  water  face  as  tight  as  possible 
against  the  entrance  of  water,  and  of  providing  drainage  under 
the  downstream  half  of  the  embankment.  For  this  reason, 
the  water  slope  of  the  dam  is  made  relatively  flat,  generally 
i  on  3  or  flatter,  and  the  downstream  slope  always  i  on  2  or 
flatter,  although  the  natural  angle  of  repose  of  the  earth  used 
may  be  nearly  as  steep  as  i  to  i.  The  gentle  slope  of  the  water 


410 


DAMS 


STORAGE  DAMS  411 

face  of  the  dam  contributes  to  its  stability  not  only  by  providing 
a  large  amount  of  weight,  but  by  giving  the  direction  of  water 
pressure  a  downward  tendency,  the  direction  of  pressure  of  a 
liquid  being  always  normal  to  the  surface  upon  which  it  is 
exerted.  The  water  pressure  on  a  3  to  i  slope  of  a  dam  being 
more  nearly  vertical  than  horizontal  increases  its  effective 
weight,  and  increases  its  stability  against  sliding,  and 
also  against  overturning  if  such  a  method  of  failure  were 
possible. 

It  appears  therefore  that  the  mass  and  shape  of  an  earthen 
dam  as  thus  determined  is  such  that  no  attention  need  be  paid 
to  its  stability  against  sliding  on  its  base  or  on  any  horizontal 
joint,  on  account  of  the  pressure  of  the  water  in  the  reservoir. 

The  other  considerations,  however,  make  the  slopes  of  the  two 
faces  of  the  dam  very  important. 

It  is  impossible  to  arrive  by  theoretical  reasoning  at  reliable 
general  rules  for  the  slopes  upon  which  any  given  materials 
will  be  stable  when  saturated  with  water.  In  general,  a  clay 
bank  when  supersaturated  has  very  little  stability,  and  the  same 
is  true  in  a  less  degree  of  a  clay  loam  and  of  a  sandy  clay  loam 
where  the  clay  content  predominates.  Where  clay  must  be  used 
it  is  very  important  to  prevent  its  saturation,  by  excluding 
the  water  so  far  as  possible,  and  providing  an  exit  for  such 
water  as  may  enter  it.  For  this  reason  it  is  desirable  to  employ 
gravel  for  the  downstream  half  of  an  earthen  dam,  as  this  will 
permit  the  slow  escape  of  contained  water,  without  danger  of 
sloughing  or  erosion.  For  the  same  reason  it  is  highly  desirable 
that  the  impervious  portion  of  the  dam  also  be  composed  largely 
of  gravel,  using  fine  sand  and  clay  only  so  far  as  necessary  to 
completely  fill  the  void  spaces  in  the  gravel. 

The  great  Gatun  Dam  on  the  Canal  Zone,  Panama,  is  built 
on  the  gentlest  slopes  of  any  dam  of  which  we  have  record. 
The  outer  slope  is  about  16  to  i  for  40  feet  in  height,  and  there 
increases  to  7  to  i,  and  finally  to  4  to  i  near  the  top.  The 
water  slope  averages  about  4  to  i  for  most  of  the  height.  The 
base  width  is  thus  2640  feet  while  the  height  is  only  105  feet, 
and  the  contents  over  21,000,000  cubic  yards. 


412  DAMS 

The  reasons  for  adopting  these  very  conservative  slopes  are 
several: 

1.  The  sluiced  clay  of  which  the  base  of  the  dam  is  com- 
posed was  considered  practically  impervious,    or  at  least  much 
less  pervious  than  the  valley  material  of  the  foundation.     The 
broad  blanket  of  sluiced  clay  confines  waters  percolating  in  the 
foundation  and  prevents  their  escape  until  they  have  traversed 
so  long  a  distance  that  the  accumulated  friction  has  destroyed 
any  possible  hydraulic  head  and  rendered  the  seepage  inert. 
At  the  same  time  any  seepage  through  the  dam  would  produce 
a  plane  of  saturation  the  surface  of  which  in  the  clay  material 
would  be  steep  enough  to  intersect  the  foundation  long  before 
reaching  the  surface  of  the  slope,  and  thus  minimize  any  possible 
tendency  to  slough. 

2.  The  adopted  method  of  construction  was  the  sluicing  of 
clay  into  the  body  of  the  dam  which  is  always  very  slow  to 
drain  and  consolidate,  and  especially  so  in  the  wet  climate  of 
Gatun,  and  it  was  necessary  to  provide  flat  slopes  for  stability 
during  construction. 

3.  It  was  desired  to  make  an  embankment  so  heavy  that  an 
alien  enemy  temporarily  in  possession  could  not  quickly  cause 
a  break  for  the  purpose  of  destroying  the  dam. 

The  practice  so  common  as  to  be  considered  almost  standard 
is  to  build  earthen  embankments  with  slopes  of  3  to  i  on  the 
water  face  and  2  to  i  on  the  outer  or  downstream  face.  These 
slopes  may  be  flattened  to  fit  cases  where  conditions  of  stability 
are  not  favorable,  and  may  be  somewhat  steeper  where  rock  or 
gravel  predominates  on  the  slopes,  or  other  conditions  favor 
unusual  stability. 

The  slopes  are  frequently  made  steeper  near  the  top  than 
lower  down,  and  this  is  a  logical  practice,  as  it  broadens  the 
base  by  the  use  of  less  material  than  required  for  uniform  slopes. 
On  the  water  face  the  steeper  slope  near  the  top  tends  to  check 
the  advance  of  waves. 

The  top  width  is  generally  made  to  vary  from  10  feet  for 
banks  of  moderate  height  to  20  feet  or  more  for  high  dams. 
The  top  should  be  slightly  crowned  to  prevent  rain  water  from 


STORAGE  DAMS  413 

standing  on  it  in  pools  and  causing  saturation.  The  top  of  the 
dam  should  be  high  enough  above  normal  high  water  so  that  no 
danger  will  ensue  of  waves  from  the  reservoir  overtopping  the 
embankment.  Where  great  wave  action  is  to  be  expected 
a  concrete  wall  is  sometimes  provided  at  the  water  edge  of  the 
top  to  break  the  waves.  See  Fig.  201. 

e.  Slope  Protection. — The  flattening  of  the  slopes  of  an 
earthen  dam,  while  increasing  its  security  against  sloughing 
and  sliding,  and  adding  to  the  security  against  the  wave  action 
upon  the  material  of  the  slope,  adds  materially  to  the  cost  by 
increasing  the  yardage,  and  on  the  water  slope  by  increasing 
the  area  that  has  to  be  protected  from  wave  action  by  pavement 
or  riprap.  Where  suitable  rock  is  abundant  for  this  purpose 
it  may  be  inexpensive,  but  in  some  cases  a  concrete  pavement 
is  necessary,  and  it  becomes  desirable,  for  reasons  of  economy 
to  reduce  this  area  to  the  smallest  dimensions.  This  reason 
led  to  the  adoption  of  slopes  for  the  Owl  Creek  Dam,  South 
Dakota,  of  2  to  i  on  the  water  side  for  the  most  part,  and  con- 
stitutes it  one  of  the  boldest  earth  dams  for  its  height  now  in 
existence.  Its  water  face  is  protected  by  a  heavy  concrete 
pavement. 

Where  rock  is  plentiful  the  water  slope  should  be  protected 
by  a  pavement  of  dry  laid  rock  not  less  than  i  foot  thick  where 
wave  action  is  moderate  to  2  feet  where  heavy  wave  action 
is  to  be  expected.  Precaution  should  be  taken  to  prevent  the 
washing  out  of  the  earthy  material  from  behind  the  pavement 
through  the  crevices.  To  prevent  this  a  layer  of  small  broken 
rock  or  screened  gravel  of  diameters  from  i  to  4  inches  should 
be  provided,  directly  under  the  pavement.  This  will  be  too 
coarse  to  wash  out  through  the  crevices  of  the  pavement,  and 
will  break  the  force  of  the  water  running  in  and .  out  of  the 
cracks  between  the  paving  stones  as  waves  advance  and  recede. 
If  rock  is  very  abundant,  and  of  poor  shapes  to  form  a  suitable 
pavement,  it  may  be  dumped  roughly  on  the  slope  without 
placing  by  hand,  but  in  such  case  a  greater  thickness  should 
be  used,  and  small  broken  rock  or  screened  gravel  should  be 
employed  for  its  foundation  as  described  above. 


414 


DAMS 


STORAGE  DAMS  415 

Where  rock  is  not  to  be  obtained  at  reasonable  cost  it  some- 
times becomes  necessary  to  protect  the  face  of  the  dam  from 
wave  action  by  the  use  of  concrete  pavement.  This  may  be 
made  in  place  on  the  slope,  or  may  be  manufactured  in  blocks  at  a 
more  convenient  point  and  placed  on  the  dam  as  paving  blocks. 
Such  blocks  should  extend  at  least  10  feet  up  and  down  the  slope, 
and  may  be  any  convenient  width  in  the  other  direction.  The 
ample  dimension  up  and  down  the  slope  is  important,  as  other- 
wise in  a  great  storm  the  receding  waves  may  leave  a  sufficient 
hydrostatic  pressure  behind  the  blocks  to  move  them  if  too  light, 
and  thus  cause  a  breach  in  the  pavement.  Such  accidents  have 
occurred  in  a  number  of  cases  in  the  region  of  the  great  plains, 
where  rock  is  scarce  and  concrete  has  been  extensively  employed 
for  paving  dams. 

Probably  the  best  form  of  concrete  pavement  yet  employed 
is  a  series  of  concrete  strips,  15  or  20  feet  wide,  running  from 
the  toe  to  the  top  of  the  dam,  with  vertical  joints  the  entire 
length  of  the  slope,  but  no  horizontal  joints.  This  pavement 
should  be  4  or  5  inches  thick  if  reinforced,  or  6  inches  if  not. 
Under  each  joint,  running  from  toe  to  top  of  the  dam,  should 
be  a  concrete  sill,  about  6  inches  square,  built  into  the  earth- 
work and  flush  with  its  surface.  After  seasoning,  the  upper 
surface  of  these  sills  should  be  oiled  or  tarred,  to  prevent  adher- 
ence to  the  concrete  slabs  afterwards  built  upon  them,  and  to 
make  a  tight  joint.  This  will  permit  these  joints  to  absorb 
the  expansion  and  contraction  in  a  horizontal  direction,  and  the 
vertical  movement  to  be  communicated  to  the  top. 

Where  rock  and  concrete  are  very  costly  and  coarse  gravel 
is  conveniently  available,  it  may  be  possible  in  some  cases  to 
depend  on  using  this  in  great  abundance  for  slope  protection,  as 
has  been  done  on  the  two  large  embankments  of  the  Deer  Fat 
Reservoir  in  Idaho. 

In  these  cases,  after  finishing  the  dam  to  a  3  to  i  water 
slope  and  20  feet  top  width,  the  top  was  widened  by  dumping 
from  cars  on  the  water  slope,  the  coarsest  gravel  available, 
which  was  sand  and  gravel  varying  from  bowlders  of  50  pounds 
weight  through  all  intermediate  sizes  to  fine  sand  and  silt,  the 


416 


DAMS 


STORAGE  DAMS  417 

proportion  of  coarse  material  varying,  but  never  great.  -  In 
this  way  the  upper  embankment  received  about  95,000  cubic 
yards  of  extra  material,  which  took  its  natural  angle  of  repose 
and  widened  the  top  of  the  embankment  from  20  feet  to  51 
to  67  feet. 

As  the  waves  of  the  reservoir  attack  the  gravel  slope  they 
gradually  undermine  and  cause  the  gravel  to  creep  down  the 
slope.  The  finest  materials  are  carried  into  the  lake  and  slowly 
deposited,  those  a  little  coarser  washed  down  to  the  toe  of  the 
slope,  and  the  other  materials  are  carried  down  less  and  less 
freely  as  they  become  coarser.  In  this  way  by  the  automatic 
sorting  of  the  water,  the  fine  materials  are  deposited  on  the 
bottom  of  the  reservoir  near  the  toe  of  the  slope  and  serve  to 
make  this  area  more  impervious.  The  coarser  sand  collected 
near  the  bottom  serves  to  give  the  bank  a  flatter  slope,  and  the 
materials,  left  on  the  slope  become  gradually  coarser  from  the 
bottom  upward,  and  the  coarsest  cobbles  and  bowlders  are 
left  on  the  upper  part  of  the  slopes  in  the  capacity  of  riprap, 
and  finally  each  material  will  take  the  slope  at  which  it  can 
resist  the  wave  action,  resulting  in  a  flattened  slope  paved  with 
water-selected  coarse  material  of  gravel  and  cobbles.  Experi- 
ence so  far  indicates  success  for  this  experiment,  with  a  large 
saving  over  the  cost  of  paving  the  slopes  with  concrete. 

/.  Percolation. — The  flow  of  water  is  ordinarily  due  to  a 
slope  in  the  water  surface.  The  action  of  gravity  causes  it  to 
move  from  the  point  where  its  surface  is  highest,  toward  the 
point  where  it  is  lowest.  This  is  true  of  a  stream,  or  a  lake, 
and  is  equally  true  of  underground  waters.  The  resistance  to 
flow  by  the  materials  of  the  soil  is  very  great,  so  that  subter- 
ranean waters  move  very  slowly,  and  their  movements  are 
further  complicated  by  capillary  action,  but  gravity  flow  depends 
upon  slope,  and  will  not  occur  without  slope. 

The  rate  of  transmission  of  water  through  any  given  soil 
varies  with  the  sine  of  the  angle  which  the  surface  of  the  per- 
colating water  makes  with  the  horizontal.  It  also  varies  with 
the  size  of  the  interstices  in  the  material  traversed.  Clay,  for 
example,  may  have  and  usually  does  have,  a  larger  percentage 


418 


DAMS 


FIG.  201. — Owl  Creek  Dam,  near  Belle  Fourche,  South  Dakota,  Showing  Concrete 

Paving. 


FIG.  202. — Upper  Deer  Flat  Embankment,  Showing  Beaching  of  Gravel  slope. 


STORAGE  DAMS 


419 


of  voids  than  sand  or  gravel,  but  they  are  so  minute  that  perco- 
lating water  is  greatly  retarded  by  friction,  and  moves  very 
slowly,  and  for  this  reason  clay  is  regarded  as  the  best  earthy 
material  to  resist  the  passage  of  water. 

After  long  and  careful  investigation  Slichter  gives  the  rate  of 
flow  for  a  grade  of  10  feet  per  mile,  in  various  materials  as 
follows : 

TABLE  XXXVII 


Material 

Miles  per  Year 

Velocity  Feet  per 
Year 

Fine  sand  

O.OI 

52.8 

Medium  sand  

o  04 

216  o 

Coarse  sand 

o  16 

84  c  o 

Fine  gravel  

1.02 

5386.0 

The  more  minute  the  openings  through  which  the  water 
must  pass,  and  the  greater  the  friction  of  passage,  the  greater 
must  be  the  slope  necessary  to  induce  a  perceptible  motion. 
Well-compacted  clay  presents  great  resistance  to  the  passage  of 
water,  and  is  therefore  very  desirable  as  a  leading  element  in  the 
upstream  half  of  the  dam. 

Since  we  cannot  make  an  earthen  bank  entirely  tight,  it  is 
important  to  make  it  so  nearly  so  that  the  slope  of  percolation 
of  water  from  the  reservoir  will  be  steep,  and  will  reach  the 
ground  before  it  reaches  the  lower  toe  of  the  dam,  so  that  the 
downstream  slope  of  the  dam  will  not  become  saturated  and 
induced  to  slough.  For  this  reason  it  is  desirable  that  the 
entire  upstream  half  of  the  dam  be  made  as  tight  as  practicable, 
and  for  the  same  reason,  some  relief  in  the  downstream  half 
is  desirable.  This  may  be  obtained  by  making  this  portion  of 
the  dam  of  coarse  material,  as  coarse  sand  or  gravel,  "which  will 
allow  small  quantities  of  percolating  waters  to  escape  freely 
without  danger  of  erosion.  The  same  result  may  be  obtained 
by  installing  under-drains  about  the  center  of  the  lower  third 
of  the  foundation.  These  methods  of  relief,  however,  should 
not  be  permitted,  unless  reasonable  tightness  is  sure  to  be 


420 


DAMS 


attained  in  the  upper  half;  for  if  spaces  of  any  size  occur  in 
the  fine  material,  the  free  escape  provided  may  permit  erosive 
velocities,  which  by  enlarging  the  channels,  may  cause  disaster. 

Fragments  of  quartz  or  granite  of  which  sand  and  gravel 
are  often  composed,  are  practically  impervious,  and  large 
fragments  of  such  material  in  an  earthen  mass  tend  to  make  it 
impervious  provided  the  spaces  between  such  fragments  are 
properly  filled. 

Following  the  above  principles  to  a  conclusion,  we  find  that 
the  tightest  mixture  we  can  make  consists  of  large  fragments  of 
impervious  gravel,  with  enough  smaller  fragments  to  fill  the 
space  between,  and  still  smaller  fragments  to  fill  the  space 
between  these,  and  so  on,  ending  with  the  finest  clay.  The 
author  has  observed  some  mixtures  in  nature  that  proved  to 
be  remarkably  water-tight  under  considerable  pressure,  two  of 
which  were  shown  by  mechanical  analysis  to  be  graded  as 
follows : 

TABLE  XXXVIII 


Material 

Passing 

Held  on 

Percentage 

No.  i 

No.  2 

Gravel 

2-inch  sieve 

8  7 

I  r    -} 

Gravel  

2-inch  sieve 

i  -inch  sieve 

9-4 

9-o 

Gravel  

i  -inch  sieve 

No.  4  sieve 

44-5 

43  -1 

Sand  

No.  4  sieve 

No.  20  sieve 

18.4 

171 

Sand  

No.  20  sieve 

No.  50  sieve 

5-i 

4-8 

Sand  

No.  50  sieve 

No.  100  sieve 

i  .4 

.   Z 

Sand  

No.  100  sieve 

No.  200  sieve 

i.4 

.  i 

Clay  and  silt  

No.  200  sieve 

ii  .  i 

10.  I 

Total  

IOO.O 

IOO.O 

Sample  No.  i  was  taken  from  near  St.  Mary  Lake,  Flathead 
Reservation,  Montana,  and  No.  2,  from  near  Lake  Kachess, 
Washington.  In  each  case  the  samples  were  taken  from  the 
sidewalls  of  test  pits  in  the  immediate  vicinity  and  far  below 
the  water  in  the  lake,  and  were  so  tight  that  practically  no 
leak  was  noticeable.  Both  samples  were  from  glacial  moraines, 


STORAGE  DAMS 


421 


unstratified,  and  thoroughly  mixed.  Classifying  the  material 
as  gravel,  sand,  and  fine  material  corresponding  in  size  to  Port- 
land cement  (taking  for  this  purpose  all  the  material  passing 
the  loo-mesh  sieve)  we  have: 


TABLE   XXXIX 


Sample  No.  i, 
Per  Cent 

Sample  No.  2, 
Per  Cent 

Gravel,  held  on  sieve  No.  4  
Sand   held  on  ^ieve  No   100 

62.6 

2A     O 

67.4 
22    A 

Fine  material  passing  No.  100  

12.5 

10.  2 

In  combining  such  materials  for  the  purpose  of  producing  a 
tight  mixture,  it  is  well  to  add  some  excess  of  the  finest  materials, 
rather  than  run  any  risk  of  leaving  unfilled  voids  between  the 
coarse  ones.  The  ratio  of  1:2:5  corresponds  almost  exactly 
with  sample  No.  i,  and  if  we  allow  for  the  small  percentage 
of  clay  and  fine  silt  usually  occurring  in  natural  sands,  we  have 
nearly  the  percentages  of  cement,  sand  and  gravel  found  in 
good  concrete,  which  is  also  designed  to  be  nearly  impervious. 
This  mixture  can  be  further  improved  by  increasing  the 
percentage  of  coarse  gravel  to  near  the  maximum  that  can  be 
used  and  still  have  the  voids  well  filled  by  finer  material.  Experi- 
ments show  that  the  amount  held  on  the  2-inch  sieve  can  with 
advantage  constitute  fully  half  of  the  mixture  when  the  parts 
are  measured  separately.  The  size,  shape  and  relations  of  the 
different  sizes  are  so  indefinite  and  so  variable  in  practice  that 
no  exact  rules  can  be  adopted  with  profit,  but  the  following 
proportions  constituted  a  rough  guide: 

Coarse  gravel,  held  on  2-inch  sieve i.oo  cu.yd. 

Fine  gravel,  held  on  No.  4  sieve 35      " 

Sand,  held  on  No.  100  sieve 40      " 

Clay  and  silt,  passing  No.  100  sieve 25      " 


Total .  .  2 .00 


These  proportions,  when  well  mixed  and  compacted    with 
a  small  quantity  of  water  and  rolled,  can  be  reduced  to  about 


422  DAMS 

if  cubic  yards  in  bulk.  Such  a  mixture  can  rarely  be  obtained 
in  practice,  but  it  gives  the  maximum  weight  and  stability, 
as  well  as  water  tightness. 

Much  discussion  has  been  held  in  the  past  regarding  the 
merits  of  the  various  types  of  earthen  dam  mentioned,  especially 
between  the  partisans  of  masonry  corewalls  as  against  those 
opposing  such  walls.  Both  types  have  their  uses,  depending 
on  the  local  conditions.  A  wooden  or  plank  core  should  never 
be  employed,  as  this  is  sure  to  decay,  and  both  before  and  after 
decay  it  affords  a  convenient  path  along  which  leakage  water 
may  freely  travel  and  find  an  outlet  if  any  exists. 

A  central  core  of  puddled  earth  is  advisable  only  when 
material  suitable  for  such  puddle  is  too  scarce  and  expensive 
to  permit  the  upstream  third  or  half  to  be  so  composed,  which 
is  better  when  feasible. 

A  masonry  corewall  affords  excellent  facilities  for  making 
connection  with  the  outlet  conduit,  with  rock  foundation  or 
abutments,  and  with  masonry  extensions  or  other  structures. 
The  corewall  may  be  necessary  in  cases  where  no  impervious 
earth  in  procurable,  or  where  it  contains  a  considerable  per- 
centage of  soluble  salts,  so  that  percolating  water  might  in  time 
carry  out  in  solution  enough  salts  to  leave  the  mass  pervious 
and  unsafe.  Such  a  case  was  the  Avalon  Dam  on  the  Pecos 
River  in  New  Mexico,  built  by  the  Pecos  Irrigation  Company, 
which  failed  in  1904,  without  overtopping.  The  most  plausible 
explanation,  being  the  gradual  leaching  of  the  sulphates  of 
calcium  and  magnesium,  until  a  finely  honey-combed  con- 
dition was  reached  after  which  a  slight  concentration  of  the 
leakage,  afforded  openings  permitting  destructive  velocities,  and 
disaster  followed.  In  the  reconstruction,  a  corewali  of  concrete 
was  used  in  the  new  portion,  and  the  remnant  of  the  old  bank 
was  provided  with  one  of  steel  sheet-piling.  These  have  now 
been  in  successful  service  over  ten  years. 

Where  these  special  reasons  for  a  corewall  do  not  exist,  the 
tendency  for  it  to  produce  supersaturation  of  the  upper  slope 
of  the  dam  is  objectionable  and  it  also  interferes  with  the  best 
consolidation  of  the  interior  of  the  embankment. 


STORAGE  DAMS  423 

The  most  general  practice  in  dam  building  in  America 
inclines  to  type  2,  where  great  effort  is  put  forth  to  make  the 
upstream  portion  of  the  dam  tight  with  selected  material  care- 
fully placed  and  compacted,  and  building  the  downstream 
portion  of  coarser  material,  affording  drainage,  and  having 
less  tendency  to  slough  when  saturated.  Frequently  this  plan 
is  supplemented  by  providing  a  corewall  of  rubble  or  concrete, 
to  insure  against  erosive  velocities  and  to  guard  against  the 
ravages  of  burrowing  animals.  The  latter  provision  is  most 
important  where  frequent  inspection  of  the  slopes  of  the  dam 
cannot  be  assured. 

Where  clay  is  the  only  material  available  for  construction, 
a  very  good  structure  can  be  secured  by  building  it  homogeneously 
in  thin  layers,  moistened  and  thoroughly  rolled.  It  is  important 
that  the  moisture  added  to  clay  be  merely  sufficient  to  permit 
compacting,  as  any  excess  of  water  in  clay  carries  a  tendency 
to  flow,  and  also  causes  swelling  which  may  lead  to  cracking  as 
the  water  is  withdrawn.  The  embankment  being  thus  finished 
nearly  dry,  any  absorption  of  water  from  the  reservoir  will  tend 
to  swelling  and  to  make  the  structure  tighter.  Such  a  structure 
is  the  Owl  Creek  Dam  of  the  U.  S.  Reclamation  Service  near 
Belle  Fourche,  South  Dakota. 

A  novel  method  of  preventing  the  saturation  of  the  down- 
stream half  of  an  earthen  dam  has  been  employed  in  the  design 
of  the  dam  built  .at  the  outlet  of  Sherburne  Lake  on  Swift  Cur- 
rent Creek  in  northern  Montana.  At  this  site  it  was  not 
practicable  to  obtain  clean  gravel  in  sufficient  quantity  for  the 
downstream  slope  to  obviate  the  danger  of  sloughing  if  the 
material  were  saturated  with  water.  To  prevent  seepage  from 
reaching  this  portion  of  the  dam  by  percolation  through  the 
upstream  half,  a  core  was  placed  about  midway  of  the  location, 
not  of  concrete  or  puddle,  to  stop  the  water,  but  of  screened 
gravel  to  receive  and  conduct  it  freely  downward  to  a  system 
of  drain  pipes  through  which  it  could  drain  into  the  stream 
below  the  dam  without  coming  in  contact  with  the  dam  below 
the  core  at  all.  This  provision  seems  to  have  accomplished 
its  purpose  perfectly. 


424  DAMS 

g.  Methods  of  Construction. — The  materials  for  constructing 
an  earthen  dam  may  be  excavated  and  transported  to  place 
in  various  ways.  Where  sand,  clay  or  loam  or  their  combina- 
tions occur  near  the  dam  site,  one  of  the  commonest  and  cheapest 
methods  is  to  plow  and  load  it  into  dump  wagons  by  means  of 
elevating  graders,  drawn  by  horses  or  by  traction  engines. 
This  method  is  well  adapted  to  localities  where  the  soil  is  shal- 
low and  underlain  by  rock.  The  dump  wagons,  drawn  by 
horses,  deposit  the  earth  while  in  motion,  and  additional  spread- 
ing is  accomplished  by  road  graders  or  Fresno  scrapers. 

Where  the  material  occurs  in  deep  deposits  so  that  a  face  of 
10  feet  or  more  can  be  obtained,  steam  shovels  may  be  employed 
to  load  it  into  dump  wagons  or  cars  in  which  it  is  transported 
to  place.  Where  the  earth  is  transported  in  cars,  it  is  often 
best  to  carry  it  to  place  on  the  dam  on  a  track  laid  on  the  embank- 
ment, and  moved  back  and  forth  as  the  work  progresses.  Some- 
times when  the  abutments  of  the  dam  are  steep,  it  is  necessary 
to  build  a  high  trestle  along  or  parallel  to  the  axis  of  the  dam, 
and  dump  the  cars  from  a  track  built  on  this  trestle.  The  cross 
braces  of  the  trestle  should  be  removed  as  the  bank  rises,  as  they 
otherwise  would  furnish  routes  for  the  lateral  passage  of  water, 
and  thus  encourage  leakage.  The  vertical  members  offer  no 
such  menace,  and  it  is  necessary  to  leave  them  in  place.  Material 
dumped  from  trestles  is  transported  to  its  place  in  the  dam  by 
means  of  scrapers,  and  may  be  further  spread  and  leveled,  with 
road  graders.  Before  sprinkling  or  rolling  it  is  best  to  remove  all 
rocks  more  than  4  inches  in  diameter,  from  the  body  of  the  dam, 
as  these  may  prevent  the  proper  action  of  the  roller,  and  leave 
uncompacted  spots  in  the  bank.  All  such  rocks  are  valuable 
parts  of  the  bank,  and  are  most  useful  on  the  upper  and  lower 
slopes,  where  they  serve  to  protect  the  dam  against  the  elements 
and  are  also  valuable  as  an  influence  against  sloughing. 

If  further  mixing  is  required,  it  may  be  secured  by  the  use 
of  a  common  two-horse  cultivator  equipped  with  4  or  6  shovel 
plows,  like  that  used  for  cultivating  row  crops. 

After  the  spreading  and  mixing  is  accomplished  it  is  generally 
necessary  to  sprinkle  with  water  in  order  to  prepare  the  material 


STORAGE  DAMS 


425 


so  it  will  "  pack."  This  may  not  be  necessary  in  wet  weather, 
or  in  a  moist  climate,  but  usually  is  in  regions  where  irrigation 
is  practiced.  The  .cheapest  method  of  sprinkling  is  to  lay  a 
3  or  4-inch  pipe  along  the  edge  of  the  embankment,  into  which 
the  water  is  forced  under  pressure  by  a  pump,  or  by  gravity  if 
practicable,  and  then  attach  hose  to  branches  of  this  pipe  at 
frequent  intervals,  from  which  the  layer  of  earth  is  sprinkled 
preparatory  to  rolling.  Care  should  be  taken  to  apply  the 
water  uniformly,  so  that  dry  spots  will  not  be  left  imperfectly 


FIG.  203. — Wheeled  Scraper. 

compacted,  and  if  considerable  clay  or  loam  occurs  in  the  material, 
the  water  applied  should  be  only  that  required  to  make  it  pack, 
as  an  excess  of  water  causes  swelling  of  clay,  and  may  cause  a 
boggy  condition  which  will  give  trouble  in  rolling,-  When  a 
bank  of  clay  is  thus  built,  nearly  dry,  any  further  absorption 
of  water  causes  some  tendency  to  swell  and  thus  further  compact 
the  material  and  increase  its  tightness. 

The  compacting  should  be  accomplished  by  spreading  in 
layers  5  or  6  inches,  sprinkling  and  rolling  with  a  traction  engine, 
or  other  suitable  roller. 


426  DAMS 

Grooved  rollers  drawn  by  horses  are  often  used,  and  the  com- 
mon road  roHer  is  sometimes  employed,  but  neither  of  these  give 
as  good  results  as  a  heavy  traction  engine,  driven  longitudinally 
along  the  embankment.  It  may  be  advisable  to  provide  such 
an  engine  with  steel  tires  to  widen  the  tread,  but  one  of  its 
chief  virtues  is  the  fact  that  it  does  not  leave  a  wide,  smooth 
plane,  as  does  a  road  roller,  but  rather  compresses  the  earth 
in  a  series  of  grooves,  and  it  also  concentrates  greater  weight 
on  each  spot  at  one  time. 

h.  Hydraulic  Fill. — Under  some  circumstances  it  is  economi- 
cal to  excavate  and  transport  the  material  to  place  in  the  dam 
by  means  of  water.  Very  good  results  may  be  obtained  by 
this  method  properly  carried  out.  To  do  this  it  is  necessary 
to  have  water  under  heavy  pressure,  so  that  delivered  through 
a  nozzle  a  stream  can  be  projected  with  sufficient  force  against 
the  material  to  be  excavated,  to  loosen  and  carry  it  away. 
This  is  then  transmitted  through  pipes  or  flumes  to  its  place  in 
the  dam.  The  necessary  pressure  to  produce  a  cutting  jet  of 
water  may  sometimes  be  secured  by  diverting  a  stream  at 
a  higher  elevation  and  bringing  it  in  a  ditch  or  flume  to  the 
vicinity  of  the  dam  site,  from  100  to  200  feet  above  the  deposit 
of  material  to  be  excavated,  so  as  to  provide  the  necessary 
head  by  gravity.  The  water  is  then  confined  in  pipes  and 
conducted  to  the  barrow  pit  where  a  hydraulic  monitor  with 
movable  nozzle  projects  it  with  force  against  the  material  to  be 
excavated. 

Where  the  conditions  do  not  permit  the  method  above 
described,  the  necessary  head  may  be  obtained  by  means  of 
large  pumps  pushing  the  water  through  pipes  of  ample  capacity, 
at  a  velocity  sufficient  to  cut  and  carry  the  material  from  the 
barrow  pit.  If,  then,  it  is  necessary  to  elevate  the  material 
to  place  it  in  the  dam,  other  pumps  may  be  installed  and  the 
material  mixed  with  water  may  be  pumped  through  pipes  and 
deposited  where  required. 

Where  the  hydraulic  method  of  transportation  is  used,  it  is 
necessary  to  build  dikes  at  the  upper  and  lower  faces  of  the  dam, 
and  discharge  the  water  laden  with  solid  material  between  them, 


STORAGE  DAMS 


427 


FIG.  204.-    Cold  Springs  Dam  under  Construction,  Umatilla  Valley,  Oregon. 


< 


FIG.  205.—  Grooved  Concrete  Roller. 


428 


DAMS 


where  the  solid  matter  is  settled  and  the  water  drawn  off  nearly 
clear.  Where  the  material  sluiced  is  all  or  mainly  clay,  it  is 
slow  to  settle,  and  remains  in  a  liquid  or  semi-liquid  condition 
for  a  long  time.  It  is  then  necessary  to  keep  the  retaining 
dikes  strong  and  heavy,  in  order  to  sustain  the  heavy  side-pres- 
sure of  the  mobile  core. 

Where  the  material  to  be  sluiced  is  mostly  clay,  a  serious 
problem  is  presented  of  draining  the  sluiced  material.  The  clay 
holds  on  to  the  contained  water  with  great  tenacity,  and  when 
saturated,  assumes  a  semi-liquid  character  which  exerts  a  hydro- 
static pressure  on  the  retaining  dikes  which  may  become  greater 
than  their  powers  of  resistance.  The  pond  of  water  constantly 
maintained  on  top  of  the  fill  is  apt  to  keep  the  mass  of  clay 


Scale  of  Feet 


-Stripped  Surface  U  u         ^Original  Surface 

DAM  AT  NECAXA,  MEXICO 

FIG.  206. 


saturated,  and  in  some  cases  the  lateral  pressure  of  the  mobile 
clay  has  broken  the  dikes  and  caused  slips.  Two  notable 
accidents  of  this  kind  have  occurred  with  very  high  dams, 
under  circumstances  so  similar  as  to  attract  widespread  atten- 
tion and  comment.  The  cases  were  the  Necaxa  Dam  in  Mexico, 
and  the  Calaveras  Dam  in  California. 

At  Necaxa  the  design  of  the  dam  was  such  as  to  give  two 
embankments  of  porous  material,  largely  rock,  resting  upon  a 
central  embankment  of  clay,  the  latter  having  theoretical  side 
slopes  of  i  to  i.  The  base  width  of  the  outside  embankments 
composed  of  rock  and  sand,  was  about  350  feet  on  the  upstream 
side,  and  250  feet  on  the  downstream  side,  leaving  for  the  cen- 
tral core  a  base  width  of  about  365  feet.  The  outer  slope  of  the 
upstream  bank  was  3  to  i,  and  that  of  the  downstream  bank 
2  to  i. 


STORAGE  DAMS 


429 


The  theory  of  the  design  was  that,  as  the  rock  embankments 
advanced  in  height  and  rested  upon  the  clay,  they  would  aid  in 
forcing  the  water  out  of  the  clay  by  the  superimposed  weight, 
so  that  the  portion  of  the  clay  underlying  the  rock  at  least 
would  become  hard,  while  the  center  would  harden  later  as  the 
weight  of  the  clay  increased.  The  materials  were  used  in  about 
the  proportions  they  occurred  in  the  pits. 

Owing  to  construction  difficulties  the  progress  of  the  upstream 
embankment  fell  behind,  and  was  frequently  left  very  narrow, 
the  place  being  filled  with  clay.  This  defect  persisted  at  a  cer- 
tain point  near  the  center  where  the  sluicing  flumes  from  the 
two  sides  should  have  met  but  did  not,  leaving  this  part  of  the 
rock  very  thin  for  a  considerable  elevation,  and  at  this  point  the 
break  occurred.  The  clay  suddenly  burst  through  the  bank 
and  flowed  out  into  the  reservoir  to  the  quantity  of  about  720,000 
cubic  yards.  Also  the  defective  bank  was  largely  composed  of  an 
eruptive  rock  having  a  specific  gravity  of  only  about  1.8,  whereas 
the  downstream  bank  was  largely  of  limestone  with  a  specific 
gravity  of  3  or  more.  The  reservoir  was  empty  at  the  time  of 
failure. 

The  Calaveras  reservoir  contained  a  depth  of  55  feet  of  water 
at  the  time  of  the  slip,  but  in  other  respects  there  was  a  strong 
similarity  of  conditions  as  shown  in  the  following  tabulation 
from  the  Engineering  News- Record: 

TABLE  XL.— TWO  Iv\RTH  DAM  SLIPS 


Xecaxa 

Calaveras 

Yardage  of  completed  dam  
Yardage  in  place  
Percentage  complete  at  slip  
Length  of  gap   feet                                      .... 

2,130,000 
1,926,000 
90.4 
39° 

3,085,000 
2,8oo,OOO 
90.7 
700 

975 

1300 

Approximate  height  of  slip,  feet  

172 

170 

The  similarity  of  yardage  in  the  two  slips,  notwithstanding 
the  longer  gap  at  Calaveras,  was  due  to  the  fact  that  no  material 
below  the  level  of  the  water  in  the  reservoir  moved. 


430  DAMS 

At  the  Calaveras  dam  a  movement  of  the  upstream  dike 
occurred  on  June  18,  1917.  Sluicing  was  immediately  stopped 
and  the  movement  continued  at  a  decreasing  rate  for  three  days 
and  then  stopped,  the  total  movement  being  between  2  and  3 
feet.  Sluicing  was  resumed  on  July  7,  and  continued  for  12 
days,  when  movement  was  again  noticed  and  sluicing  was 
stopped.  The  steam  shovel  work  on  the  dikes  was  continued, 
however,  and  each  dike  widened  60  feet  into  the  pool  and  raised 
30  feet  or  so.  The  central  core  of  liquid  clay  was  raised  12  feet 
by  the  sinking  of  the  rock-fill  into  it.  On  February  12,  1918, 
sluicing  was  resumed,  and  again  stopped  on  March  4,  on  account 
of  further  movement,  which  continued  irregularly  until  March 
24  when  the  failure  occurred  as  a  sudden  movement.  The 
upstream  dike  broke  and  the  liquid  clay  flowed  out  into  the 
reservoir,  overturning  and  burying  the  outlet  tower.  These  two 
accidents,  as  well  as  small  slips  at  the  Gatun  Dam  and  else- 
where, emphasize  the  importance  of  providing  self-sustaining 
stable  dikes  to  confine  sluiced  clay,  during  the  very  slow  hard- 
ening process. 

Where  the  material  sluiced  into  the  dam  contains  coarse 
elements,  as  gravel  or  rock  fragments,  it  is  desirable  to  deposit 
this  on  the  slopes  of  the  dam,  and  the  finer  material  in  the 
interior,  where  it  will  form  a  tight  puddle  core.  The  coarse 
material  placed  on  the  water  slope  will,  if  sufficiently  coarse 
and  abundant,  protect  the  dam  from  the  destructive  action 
of  the  waves,  and  that  en  the  •  lower  slope  will  protect  it 
against  the  erosion  of  wind  and  rain,  and  on  both  slopes  will 
guard  against  sloughing.  The  entire  body  of  the  dam  being 
of  sluiced  material  settled  in  water  will,  if  properly  consti- 
tuted and  disposed  as  above  described,  form  an  ideal  structure 
in  stability  and  efficiency  for  its  purpose.  Fig.  207  illustrates 
the  method  of  transporting  mixed  materials  and  disposing  them 
as  above  described.  Parallel  flumes  are  built  lengthwise  of  the 
dam,  which  receive  the  materials  brought  from  the  pit.  These 
flumes  are  provided  with  gates  on  both  sides  that  can  be  opened 
and  closed  at  will,  and  at  the  point  where  it  is  desired  to  dis- 
charge the  load,  an  iron  screen  or  grillage  with  openings  large 


STORAGE  DAMS 


431 


432  DAMS 

enough  to  pass  most  of  the  sluicing  materials,  but  small  enough 
to  stop  the  coarsest,  is  placed  in  the  flume  at  an  angle  of  about 
45  degrees,  just  below  an  open  gate  on  the  side  of  the  outer 
slope  of  the  dam,  and  this  grillage  deflects  the  coarse  material 
which  falls  on  the  slope,  while  the  water  carrying  the  finer 
material  rushes  through  and  is  discharged  on  the  inner  side 
into  the  central  pond.  As  it  falls,  the  coarsest  of  the  material 
is  deposited,  and  the  water,  no  longer  confined  to  a  narrow 
channel,  can  carry  only  the  sand  and  clay.  As  the  slope  flattens 
the  sand  is  deposited,  the  coarsest  first,  and  the  fine  nearer  the 
pond,  while  the  clay  and  impalpable  silt  is  carried  into  the  pond, 
and  settles  but  slowly.  A  weir  is  provided  where  the  surface 
water  is  drawn  off  at  a  point  as  remote  as  convenient  from 
where  the  water  enters  the  pond  with  its  load  of  silt.  There 
is  always  a  tendency  to  stratification  in  the  central  pond,  and 
due  precaution  must  be  taken  to  prevent  continuous  strata 
of  sand  from  extending  through  the  puddle  core,  as  this  would 
furnish  an  opportunity  for  the  passage  of  water.  Such  strata 
may  be  broken  up  by  men  wading  about  in  the  pond,  and  plung- 
ing boards  or  paddles  into  the  mud  as  far  as  possible  in  such 
a  position  as  to  cut  the  strata  and  permit  the  deposit  of  clay 
in  the  cavities  made  by  the  paddles. 

Hydraulic  methods  are  best  adapted  to  mixed  materials, 
as  the  sorting  capacity  of  water  can  be  utilized  to  separate  the 
different  sizes  and  produce  outer  slopes  of  rock  or  gravel,  which 
have  no  tendency  to  slough,  and  will  resist  the  action  of  waves 
on  the  water  side  and  the  wind  and  rain  on  the  other.  The 
finer  material  can  thus  be  concentrated  in  the  center,  where  if  it 
contains  considerable  loam  or  clay  it  forms  a  puddle  core  and 
imparts  a  water-holding  capacity  to  the  structures. 

Sometimes  it  is  found  desirable  to  excavate  and  transport 
the  material  to  the  dam  by  dry  methods,  deposit  it  in  dikes  along 
both  faces,  and  then  wash  a  portion  of  it  into  the  center  with  a 
hydraulic  jet,  forming  a  pond  in  the  center  and  producing  a 
puddle  core.  This  combination  of  hydraulic  and  mechanical 
methods  is  best  adapted  to  localities  where  the  material  is  a 
mixture  of  coarse  and  fine,  with  many  rocks  too  large  to  be 


STORAGE  DAMS 


433 


transported  with  water 
or  consolidated  with  a 
roller,  and  too  numerous 
to  be  rejected. 

Except  where  the  hy- 
draulic method  is  used, 
it  is  best  to  put  the 
finest  and  most  imper- 
vious material  near  the 
water  face,  and  if  enough 
of  this  is  readily  available, 
one-half  or  two-thirds  of 
the  dam  should  be  so 
built,  leaving  the  lower 
third  to  be  built  of  gravel 
or  other  coarser  material, 
grading  from  fine  to 
coarse  as  gradually  as 
convenient,  so  that  the 
coarsest  material  used  is 
on  the  downstream  face. 

The  transition  from 
fine  to  coarse  material 
should  be  as  gradual  as 
possible,  however,  to  pre- 
vent any  tendency  for 
percolating  waters  to 
carry  the  fine  material 
through  the  gravel.  The 
ideal  condition  is  analo- 
gous to  a  filter,  where  a 
very  fine  material  is  em- 
ployed on  the  water  side 
and  becomes  very  gradu- 
ally coarser  in  the  di- 
rection of  the  flow  of 
water.  The  voids  being 


434  DAMS 

everywhere  too  small  for  the  passage  of  the  finest  particles 
of  earth  in  their  vicinity.  At  least  one-third,  however,  and 
better  still  one-half  or  two-thirds  of  the  dam  on  the  water  side, 
should  be  made  as  tight  as  possible.  There  is  decided  advantage, 
however,  in  having  the  downstream  part  of  the  dam  composed  of 
gravel,  as  this  has  no  tendency  to  slough  when  wet,  and  it  is 
practically  impossible  for  percolating  water  to  erode  channels 
through  gravel,  as  it  will  not  bridge  over  like  clay  or  loam, 
but  will  generally  fall  into  any  cavity  formed  and  clog  it.  It 
thus  offers  ready  and  safe  drainage  for  any  waters  that  may 
percolate  through  the  upstream  part  of  the  dam,  and  prevents 
saturation  of  the  interior,  with  its  tendency  to  slough.  For 


Adjustable  Spillway  Crest  and  ^e^^*^3^J^!]^/GraVel 

Maximum  Water  Surface  E1.4793^^  -JT'Hi'Vv 

=  _-ZZL-=T^^r       IJ^fe^—GravelCore 
Permanent  Crest  of  Spillway,  El.i7SS-/^<^^»s(*T!oncret 

Parapet  W   Coarser  "^.-^"Gravel 

El          iic-i :-l    ^<«£,. 

elected  Mater 
d  and  Rol 


FIG.  209. — Section  of  Sherburne  Lake  jL.jam,  showing  Gravel  Core  and  Drains 
to  Provide  for  Seepage  Water. 

these  reasons,  gravel  is  a  very  valuable  building  material  for 
dams,  canal  banks,  and  many  other  irrigation  requirements. 
Even  the  impervious  portion  may  be,  and  preferably  should  be 
largely  of  gravel,  as  we  have  seen,  although  it  requires  an  admix- 
ture of  finer  materials  to  make  it  tight.  An  advantageous 
use  of  gravel  in  an  earthen  dam  is  illustrated  in  Fig.  209.  In 
this  case  it  was  difficult  to  obtain  sufficient  gravel  to  form  the 
entire  downstream  half  of  the  dam,  and  so  a  core  of  screened 
gravel  10  feet  thick  was  placed  in  the  axis  of  the  dam  to  receive 
any  water  that  might  percolate  through  the  upstream  half  of 
the  dam  and  conduct  it  readily  to  the  base,  where  it  is  carried 
away  by  tile  drains.  This  is  to  prevent  the  saturation  of  the 
lower  half  of  the  dam  and  the  consequent  tendency  to  slough. 
The  screening  of  the  gravel  was  for  the  purpose  of  removing 


STORAGE  DAMS 


435 


436 


DAMS 


any  sand  which  would  tend  to  clog  and  render  the  drainage 
imperfect. 

Fig.  196  illustrates  another  use  of  gravel,  on  the  lower  toe 
of  the  Owl  Creek  Dam.  This  gravel  was  hauled  a  long  distance, 
and  placed  in  position  to  load  the  foundation  at  the  lower  toe, 
where  seepage  under  the  dam  might  soften  the  earth.  The 
gravel  prevents  any  tendency  to  slough,  while  allowing  seepage 
waters  to  escape  harmlessly. 

4.  Rockfill  Dams. — The  rule  that  earthen  dams  should  be 
built  of  material  fine  and  water  tight  on  the  water  face,  and 
grade  very  gradually  into  coarser  material  toward  the  down- 


CROSS  SECTION  OF  LOOSE-ROCK  AND  EARTH  DAM 


40         60 

SCALE  OF  FEET 


FIG.  211. — Rock-Fill  Dam,  Snake  River,  Minidoka  Project,  Idaho. 

stream  face,  suggests  a  combination  often  employed,  of  earth  and 
rock-fill,  where  earth  is  used  on  the  side  toward  the  reservoir, 
and  loose  rock  on  the  other  side.  The  transition,  however,  should 
be  as  gradual  as  possible,  to  prevent  any  leakage  from  washing 
the  earth  through  the  rock-fill  and  causing  a  breach.  If  suitable 
earth  is  plentiful  near  by,  it  is  much  cheaper  to  place  than  the 
rock,  and  will  naturally  predominate,  but  where  it  is  scarce, 
or  must  be  transported  a  long  distance,  economy  may  require 
the  use  of  rock  in  the  main  body  of  the  dam,  with  only  enough 
earth  to  form  a  water-tight  blanket  on  the  water  face.  Where 
insufficient  earth  for  this  purpose  is  available,  it  becomes  neces- 
sary to  secure  water-tightness  by  other  methods,  and  we  have  the 
rock-fill  type,  pure  and  simple. 

Where  a  dam  is  built  of  loose  rock,  it  is  necessary  to  employ 
some  special  measures  to  secure  water-tightness.     This  is  some- 


ROCKFILL  DAMS 


437 


times  obtained  by  providing  a  deck  of  lumber  on  the  water  face, 
carefully  caulked  and  fastened  to  timbers  built  into  the  rock. 
The  lumber  deck  should  be  liberally  treated  with  asphalt  or 


PLAN 


C ft oss     SECTION 

FIG.  212. — Plan  and  Cross-section  of  Bowman  Dam. 

durable  paint  to  preserve  it  from  warping  and  deterioration, 
and  it  should  be  inspected  and  repaired  whenever  the  water  is 
drawn  out  of  the  reservoir. 


438 


DAMS 


Steel  has  also  been  employed  to  form  a  water-tight  deck 
on  a  loose-rock  dam,  and  serves  the  purpose  well  if  protected 
from  oxidation.  It  must  have  frequent  expansion  joints  to 
provide  for  changes  in  temperature. 

In  some  cases  a  corewall  of  masonry  is  built  in  the  center  to 
secure  water-tightness,  and  in  one  case,  the  lower  Otay  Dam 
in  Lower  California  (Fig.  214)  a  diaphragm  of  steel  was  employed 
in  conjunction  with  the  corewall.  This  diaphragm  was  one- 
third  of  an  inch  thick  near  the  base,  and  one-quarter  of  an  inch 


ELEVATION 

FIG.  213. — Elevation,  Plan,  and  Cross-section  of  Castle  wood  Dam,  Colorado. 

in  the  upper  part.  It  was  anchored  firmly  to  the  masonry 
foundation,  and  coated  with  asphalt  applied  hot.  A  layer  of 
burlap  was  applied  to  the  asphalt  while  still  hot,  and  over  this 
a  harder  grade  of  asphalt  wp,s  applied,  and  the  whole  was  encased 
in  a  rubble  masonry  wall  laid  in  Portland  cement  concrete. 
This  wall  was  6  feet  thick  at  the  base,  tapering  to  2  feet  at  the 
height  of  8  feet,  which  thickness  was  maintained  to  the  top. 

The  top  width  of  the  dam  was  12  feet,  and  the  rock  was 
dumped  in  place  with  face  slopes  about  i  to  i.  The  dam  was 
150  feet  high  above  the  bottom  of  foundation,  and  565  feet  long 


ROCKFILL  DAMS 


439 


440 


DAMS 


FIG.  215. — Elevation  and  Cross-section  of  Walnut  Grove  Dam. 


•  Vv.-,..-r:.<.».^      ,',      oo.    40-     60' ' 

gSg/^-z^  '/<~12/L J 

CROSS-SECTION  OF  DAM 

FIG.  2 1 6.— Rock-filled  Steel-core  Dam,  Lower  Otay,  Cal. 


ROC KF ILL  DAMS  441 

on  top,  forming  a  reservoir  of  42,000  acre-feet  capacity.  A 
few  hundred  feet  east  of  the  dam  a  channel  was  cut  through 
the  rock,  30  feet  wide,  to  a  depth  10  feet  below  the  crest  of  the 
dam,  to  form  a  spillway.  This  proved  to  be  insufficient,  and 
in  the  great  storm  of  January,  1915,  the  reservoir  filled  and  the 
dam  was  overtopped  by  the  flood  and  destroyed.  The  drainage 
area  is  about  12  square  miles,  and  the  capacity  of  the  spillway 
about  5000  feet  per  second,  with  water  standing  even  with  the 
crest  of  the  dam. 

The  Walnut  Grove  Dam  in  Arizona  is  another  case  of  a  rock- 
fill  dam  that  was  washed  out  by  overtopping  of  the  structure 
by  a  great  flood  wave.  These  failures  do  not  condemn  the 
rock-fill  type  of  construction,  but  emphasize  the  importance  of 
providing  abundant  spillway  capacity  so  that  by  no  possibility 
can  the  dam  be  overtopped  by  flood  waters.  For  similar  rea- 
sons it  is  desirable  that  the  largest  and  best  rocks  obtainable  be 
placed  at  and  above  the  downstream  toe  of  the  dam,  to  resist 
any  excessive  leakage  that  might  accidentally  occur.  When 
properly  built  of  good,  sound,  durable  rock,  and  supplemented 
by  an  ample  spillway,  the  rock-fill  type  of  dam  has  no  superior 
for  safety  and  permanency,  and  has,  indeed,  some  apparent 
advantages  in  resisting  earthquake  shocks, 


CHAPTER  XVIII 

MASONRY  DAMS 

MASONRY  DAMS  may  be  classified  with  reference  to  their 
materials  of  construction  into  four  main  types : 

1.  Coursed  masonry,  or  cut  stone  laid  in  cement  mortar. 

2.  Rubble  masonry,  or  rough  uncoursed  stone  laid  in  cement 
mortar  or  concrete. 

3.  Cyclopean   concrete   or   concrete   with   large    stones    or 
"  plums  "  embedded  therein. 

4.  Plain  concrete. 

Where  rock  is  of  best  quality,  coursed  cr  ashlar  masonry  will 
require  the  minimum  quantity  of  cement,  and  will  also  afford 
the  maximum  weight  and  resistance  to  crushing,  since  this 
type  employs  the  maximum  proportion  of  stone  and  the  mini- 
mum of  mortar,  and  first-class  stone  is  both  heavier  and  stronger 
than  any  mortar  or  concrete  that  can  be  made. 

By  reason  of  the  courses  it  is  less  firmly  bonded  together 
than  other  types  of  masonry,  and  may  have  therefore  less 
shearing  strength  along  horizontal  courses.  The  work  of  shap- 
ing the  stones  also  involves  expense,  and  for  these  reasons 
ashlar  masonry  is  not  often  used  unless  cement  is  very  costly 
or  a  good  appearance  is  especially  desirable. 

Rough  uncoursed  rubble  requires  .more  cement,  but  unless 
cement  is  very  costly  is  generally  cheaper  than  ashlar  because 
of  less  labor  involved,  and  its  random  character  and  use  of  very 
large  rock  bind  the  dam  together  into  a  monolith,  and  thus 
give  it  greater  shearing  strength,  with  less  tendency  to  crack. 
This  type  is  much  used  and  is  very  desirable  and  economical 
where  good  rock  is  abundant.  The  stones  are  usually  embedded 
in  cement  mortar,  while  concrete  may  be  used  to  fill  vertical 
joints. 

442 


CLASSIFICATION  OF  MASONRY  DAMS  443 

Cyclopean  concrete  has  large  and  small  rock  embedded  in  it, 
and  differs  from  rubble  mainly  in  the  fact  that  the  former  uses 
rock  to  a  greater  extent,  while  in  the  latter  concrete  predominates. 
It  requires  less  manual  labor,  and  is  cheaper  under  most  cir- 
cumstances, while  giving  very  satisfactory  results.  It  is  now 
more  generally  employed  than  any  of  the  other  types. 

The  fourth  type,  Plain  Concrete,  is  used  where  good  rock 
is  not  convenient,  and  gives  good  results,  though  not  so  heavy 
nor  theoretically  quite  so  strong  as  the  other  types,  unless 
reinforced  with  steel. 

i.  Classification  of  Masonry  Dams. — Dams  built  of  masonry 
may  be  divided  into  two  classes  according  to  their  design: 

1.  Gravity  Dams,  or  those  depending  for  stability  entirely 
upon  their  weight. 

2.  Arch  Dams,  or  those  depending  for  stability  mainly  upon 
their  action  as  an  arch,  by  which  the  water  pressure  is  trans- 
mitted to  the  abutments. 

There  are  many  instances  of  dams  in  service  that  would 
instantly  fail  under  water  pressure  if  weight  were  the  only 
dependence  for  stability.  They  are  curved  in  plan,  and  resist 
the  pressure  of  water  by  arch  action.  On  the  other  hand  there 
are  also  many  dams  which  are  straight  and  cannot  possibly 
act  as  arches,  and  are  stable  only  because  of  their  weight.  Since 
every  masonry  dam  must  have  considerable  weight,  this  con- 
stitutes in  every  case  an  important  element  of  its  stability, 
and  the  two  types  merge  into  each  other  in  a  very  indefinite 
manner. 

Many  high  dams  have  been  built  on  gravity  lines,  theoretic- 
ally safe  as  gravity  structures,  but  also  curved  to  form  an  arch 
as  an  added  assurance  of  stability.  Intermediate  types  with 
scant  gravity  section  but  arched  in  plan,  and  others  of  gravity 
section  and  only  slightly  curved  have  also  been  constructed. 

Some  curvature  of  plan  is  always  desirable  in  every  masonry 
dam,  and  should  be  provided  unless  the  expense  is  excessive. 
Whatever  its  coefficient  of  safety  as  a  gravity  structure,  this 
can  be  increased  by  curving  the  plan,  so  that  the  dam  can 


444  MASONRY  DAMS 

neither  slide  nor  overturn  without  crushing  the  masonry  or  its 
abutments.  This  precaution  does  not  prevent  nor  interfere 
with  the  stability  due  to  gravity  and  cohesion,  and  only  comes 
into  play  to  supplement  them  in  case  they  prove  insufficient, 
and  the  arch  action  takes  only  those  stresses  which  are  beyond 
those  provided  for  by  gravity. 

2.  Methods  of  Failure. — A  masonry  dam  may  fail  by  any 
one  or  more  of  three  methods: 

(a)  By  sliding  on  the  foundation  or  on  any  horizontal  joint. 

(b)  By  overturning  around  the  downstream  toe  or  any  part 
of  the  downstream  slope  as  a  fulcrum. 

(c)  By  crushing  the  foundation  or  the  masonry. 

(d)  By  undermining  the  foundation,  either  by  blacklash  of 
water  pouring  over  the  top,  or  by  piping  underneath  the  dam 
by  water  under  pressure. 

Failures  sometimes  occur  by  a  combination  of  the  above 
causes.  For  example  the  excavation  of  a  deep  hole  by  water 
falling  below  the  toe  of  a  dam  on  a  weak  foundation  may  remove 
the  supporting  rock  to  such  an  extent  as  to  cause  failure  by 
sliding  or  overturning,  which  might  not  have  occurred  had  the 
toe  been  properly  protected. 

A  masonry  dam  generally  has  an  indefinite  but  important 
element  of  strength  due  to  the  cohesion  of  its  parts,  if  care  be 
taken  to  make  it  of  monolithic  character.  This  is  an  added 
security  especially  against  failure  by  sliding  on  a  joint  of  the 
masonry,  as  this  also  involves  in  that  case  the  shearing  of  the 
monolith  along  that  joint.  This  applies  especially  to  gravity 
dams,  the  monolithic  character  being  not  quite  so  important 
in  arch  dams,  which  cannot  fail  without  crushing  the  masonry 
or  abutments,  except  by  undermining. 

3.  Pressures  in  Masonry. — One  of  the  first  questions  arising 
in  the  design  of  a  high  masonry  dam  is  the  safe  limit  of  pressure 
in  the  masonry  and  in  the  foundation.     There  are  really  two 
questions  requiring  careful  consideration,  namely,  the  bearing 
power  of  the  natural  rock  in  place,  and  the  crushing  strength 
of  the  concrete.     If  the  foundation  is  a  good  quality  of  lime- 


PRESSURES  IN  MASONRY  445 

stone,  sandstone  or  crystalline  rock,  it  will  sustain  a  greater 
pressure  than  any  concrete,  and  the  problem  is  reduced  to  the 
question  of  safe  pressures  on  concrete,  as  this  must  in  the  base 
sustain  substantially  the  same  pressures  as  the  foundation.  If, 
however,  the  rock  is  one  of  the  numerous  varieties  of  soft  rock 
or  shale  it  should  be  carefully  tested  for  its  bearing  power.  This 
may  be  done  by  carefully  smoothing  a  measured  portion  of  the 
rock  in  place,  building  a  concrete  block  upon  it,  and  loading 
this  with  steel  rails  or  other  heavy  material  to  an  amount 
greater  than  the  load  it  is  desired  to  have  it  carry  in  the  con- 
struction. Any  subsidence  should  be  carefully  noted,  and  the 
experiment  should  be  repeated  on  various  parts  of  the  rock  in 
question,  especially  if  it  appears  to  vary  in  quality.  Weak  zones 
are  to  be  feared  most  near  the  toe  of  the  dam,  and  next  to  this 
in  importance  is  that  at  the  heel.  The  interior  parts  of  the 
foundation  have  less  maximum  load,  and  are  confined  so 
thoroughly  that  they  will  sustain  higher  pressures.  If  tests  of 
rock  near  the  toe  show  notable  yielding  under  the  load  to  be 
imposed,  the  limits  of  pressure  must  be  lowered  by  spreading 
the  base  or  otherwise,  until  they  can  be  safely  carried  by  the 
material  available. 

The  safe  bearing  loads  for  natural  rock  is  a  very  broad 
subject  upon  which  much  has  been  written  and  many  experi- 
ments have  been  made.  Many  elaborate  formulas  have  been 
proposed  for  computing  the  bearing  power  of  various  natural 
soils,  but  the  impossibility  of  accurately  defining  the  properties 
of  the  many  variable  materials  prevents  any  exact  mathematical 
treatment  of  the  subject.  For  the  same  reason  it  is  difficult 
to  formulate  any  but  rough  rules  for  guidance. 

Pure  clay  is  poor  foundation  wherever  it  is  subject  to  satura- 
tion, as  it  becomes  plastic  when  wet,  and  unless  thoroughly 
confined  when  in  that  condition,  has  little  bearing  power.  If 
well  compacted,  and  heavily  loaded,  it  excludes  the  water  to 
such  an  extent  that  it  will  safely  sustain  a  pressure  of  4  tons 
per  square  foot. 

Sand  has  safely  carried  loads  of  from  4  to  5  tons  to  the  square 
foot,  and  gravel  will  carry  still  more.  Soft  rock  and  shale  have 


446  MASONRY  DAMS 

been  safely  loaded  to  the  extent  of  8  to  10  tons,  and  harder 
rocks  will  carry  much  heavier  loads  with  safety,  reaching  in 
the  case  of  granite  a  crushing  strength  of  hundreds  of  tons  per 
square  foot.  Any  good  sandstone,  or  limestone,  or  any  rea- 
sonably hard  rock  has  a  higher  crushing  strength  than  cement 
mortar  or  concrete,  and  hence  the  safe  bearing  loads  upon 
masonry,  where  good  rock  is  used,  depend  upon  the  quality  of 
the  mortar  or  concrete  with  which  the  masonry  is  bonded,  and 
the  thinner  the  mortar  joints  the  greater  bearing  power.  For 
this  reason  ashlar  or  cut-stone  masonry  with  thin  joints  has 
especially  high  resistance  to  crushing. 

As  concrete  is  nearly  always  used  in  compression,  it  is  impor- 
tant to  make  crushing  tests  upon  samples  to  be  used  in  any 
important  structure.  These  tests  are  usually  made  upon  6-inch 
cubes,  or  upon  cylinders  6  inches  in  diameter.  Any  of  the 
standard  testing  machines  are  satisfactory  for  this  purpose, 
and  if  such  are  not  obtainable,  the  test  pieces  may  be  loaded 
with  pig  iron,  sacks  of  cement,  or  other  convenient  heavy 
materials  of  known  weight,  or  more  conveniently,  a  lever  may 
be  used  and  an  equivalent  test  made  with  much  less  weight. 
It  is  important  that  such  tests  be  made  to  try  out  the  sand  and 
gravel  to  be  used,  as  these  are  sometimes  unsuitable,  without 
showing  any  signs  of  their  defects  except  upon  test. 

Table  XLI  gives  some  pressures  of  actual  service  conditions, 
and  some  tests  to  destruction. 

Creager  gives  the  following  for  the  compression  strength  of 
concrete  of  various  combinations;  in  pounds  per  square  foot: 

Proportions.  Age  I   Month.  Age  6  Months. 

1:2:4  35°>000  470,000 

1:2^:5  310,000  420,000 

1:3:6  280,000  380,000 

1:4:8  230,000  300,000 

1:5:10  180,000  250,000 

i :  6 : 1 2  1 50,000  200,000 


FAILURE  BY  SLIDING 
TABLE  XLL— PRESSURES  ON  MASONRY 


447 


Structure 

Material 

Pressure 
per 

Sq.ft. 
Tons 

Authority 

Bridge  Pont-y  Prydd,  Wales. 

Limestone  rubble  .  . 

20.7 

I.  O.  Baker 

Brooklyn  Bridge  

Granite  ashlar  

39-5 

Duryea  and  Mayer 

Washington  Monument  

Cut  marble  

25-4 

Col.  T.  L.  Casey 

St.  Louis  Bridge  

Cut  limestone  

38-0 

Hist.  St.  Louis  Bridge 

Rookery  Building,  Chicago.  . 

Cut  granite 

30  .  o 

I.  O.  Baker 

Bear  Valley  Dam 

Granite  rubble  .... 

40  .  o 

J.  D.  Schuyler 

All  Saints  Church,  Angers  .  .  . 

Forneaux  stone.  .  .  . 

43.0 

J.  T.  Fanning 

Chapter  House,  Elgin  

Red  sandstone  

20.  O 

" 

St.  Paul's,  London  

Portland  limestone. 

19-7 

•  ' 

St.  Peter's,  Rome  

Calcarious  tufa.  .  .  . 

16.7 

" 

Various  Arch  Bridges  

Cut  masonry  

60  .  o 

« 

Estacado  Hollow-Dam  

Concrete  

17.5 

" 

Vrynwy  Dam  Prisms  

Concrete  

181  .0 

Tests  by  Sir  Andrew  Clarke 

Roosevelt  Dam,  Arizona.  .  .  . 

Quartz  rubble  

23.0 

U.  S.  Reclamation  Service 

Shoshone  Dam,  Wyoming.  .  . 

Concrete  

21  .O 

" 

Arrowrock  Dam,  Idaho  

Concrete.  

30.O 

"                   " 

Elephant  Butte  Dam,  N.  M. 

Concrete  

14.2 

" 

Kensico  Dam,  N.  Y  

Concrete  

15.8 

A.S.C.E.    Transactions,    Vol. 

75.  p.  170 

Olive  Bridge  Dam,  N.  Y  .  .  .  . 

Rubble  

15-4 

Morrison  and  Brodie 

Burrin  Juick  Dam,  Australia 

21  .O 

Bligh,  Dams  and  Weirs,  p.  66 

Barossa  Dam 

17.2 

P.   112 

Lithgow  Dam. 

13  .  o 

P.    112 

Granite  Ashlar  

Test  specimens.  .  .  . 

583 

Austrian  Soc.  Eng.  and  Arch. 

Sandstone  Rubble  

Test  specimens.  .  .  . 

I84 

it                     ii 

Gravel  Concrete  1:2:3.... 

Test  specimens  .... 

128 

ii 

Gravel  Concrete  1:3:5.. 

Test  specimens  .  .  . 

66 

4.  Failure  by  Sliding. — The  number  of  failures  of  dams  from 
sliding  on  their  foundations  emphasizes  the  necessity  and 
importance  of  taking  such  precautions  as  to  insure  against  its 
occurrence.  The  first  essential  is  to  provide  the  dam  with 
sufficient  weight  to  overcome  the  tendency  to  slide  with  the 
coefficient  of  friction  to  be  expected.  This  coefficient  of  friction, 
however,  is  so  uncertain  as  to  be  practically  indeterminate 
except  very  roughly.  The  difficulty  is  to  learn  exactly  the 
conditions  that  exist  in  the  foundation,  and  that  will  exist  after 
construction  of  the  dam.  These  may  vary  at  any  point,  and  our 
investigations  may  be  at  points  not  truly  representative.  Great 
dependence,  therefore,  must  finally  be  placed  on  expert  judgment, 
after  weighing  all  the  obtainable  evidence.  A  few  simple  rules 
are,  however,  of  value  in  this  connection.  The  following 


448 


MASONRY  DAMS 


values  for  friction  have  been  published,  but  should  be  accepted 
with  caution,  because  of  the  impossibility  of  reproducing  the 
exact  conditions: 


TABLE  XLII.— EXPERIMENTAL  COEFFICIENTS  OF  FRICTION 


Materials 

Coefficient 

Authority 

Masonry  and  brickwork,  dry  
Masonry  and  brickwork,  with  wet  mortar  
Masonry  and  brickwork,  on  dry  clav  

.65 
•47 
rj 

Morin 

<  i 

(  i 

Masonry  and  brickwork,  on  moist  clay  . 

?  2 

1  1 

Soft  limestone  on  hard,  well-dressed  

65 

i  ( 

Soft  limestone  on  soft   wcll-dre^seJ 

67 

1  1 

White  clay,  fine  grained,  wet  
White  clay,  fine  grained   moist 

•34 

4.2 

Scheidenhelm 

:  i 

Yellow  clay,  containing  some  grit  
Yellow  clay,  moist. 

.68 
83 

1  1 

Yellow  clay  very  wet 

ro 

i  t 

Black  loam,  moist  
Black  loam,  wet 

•74 

72 

t  1 
1  1 

Black  gumbo,  wet  

71 

i  ( 

If  the  foundation  is  of  material  horizontally  stratified,  or 
nearly  so,  especial  care  must  be  taken  to  exclude  water  from  the 
foundation  and  to  afford  easy  means  of  exit  for  any  small 
quantity  which  enters. 

An  imperative  requirement  in  the  design  of  a  gravity  masonry 
dam  is  that  there  shall  be  no  tension  in  the  masonry  on  the  face 
of  the  dam  which  is  exposed  to  water  pressure.  Should  any 
tension  occur  here  it  will  tend  to  form  horizontal  cracks  or  to 
open  existing  cracks  and  permit  the  entrance  of  water  under 
pressare  and  thus  produce  flotation  or  uplift,  which  in  turn 
would  increase  any  tendency  to  slide  or  overturn  the  masonry 
above  the  cracks.  Tension  of  the  masonry  at  other  points 
while  undesirable,  is  not  nearly  so  dangerous  as  on  the  water 
face.  Where  conditions  permit,  one  of  the  surest  and  cheapest 
methods  of  providing  an  ample  factor  of  safety  against  sliding 
in  spite  of  uplift  in  the  foundation,  is  to  build  the  dam  on  a 
curve  convex  upstream.  If  this  be  done,  it  cannot  slide  nor 


FAILURE  BY  OVERTURNING  449 

overturn  without  crushing  either  the  masonry  or  its  abutments. 
Any  good  masonry  is  well-adapted  to  withstand  compressive 
stresses,  and  it  is  on  this  that  reliance  should  be  placed  when 
feasible.  It  is  sometimes  urged  that  with  a  moderate  curve 
to  a  long  radius  the  compression  on  the  voussoirs  of  the  arch 
and  the  abutments  would  exceed  safe  limits.  This  argument 
is  based  on  the  assumption  that  all  the  pressure  upon  the  dam 
is  taken  by  the  arch  and  transmitted  to  the  abutments.  This 
is  impossible.  Since  it  is  impossible  to  deprive  a  masonry  dam 
of  its  weight,  it  has  resistance  as  a  cantilever  irrespective  of 
its  plan,  and  no  strains  can  be  transmitted  by  the  arch  to  the 
abutments  until  the  resistance  due  to  gravity  and  shear  have 
been  brought  into  play.  The  arch  can  be  made  to  take  only 
the  residue,  and  if  large  strains  are  transmitted  to  the  abut- 
ments, it  merely  emphasizes  the  necessity  of  the  curved  plan, 
and  proves  that  a  straight  dam  on  the  same  section  would  be 
likely  to  fail. 

5.  Failure  by  Overturning. — The  tendency  of  a  masonry 
dam  to  overturn  is  in  practice  less  than  appears  from  a  theo- 
retical examination  of  any  short  section  of  the  dam.  The  ten- 
dency to  overturn  of  such  a  short  section  of  the  dam,  if  near 
the  center,  is  met  by  the  necessity  of  shearing  away  from  the 
adjoining  sections,  and  the  shearing  strength  of  so  large  a  mass 
of  good  masonry  is  very  great.  The  foundation  of  the  dam  is 
usually  V-shaped,  and  the  whole  dam  cannot  overturn  on  the 
lowest  point  of  the  foundation  as  a  fulcrum,  and  the  only  line 
available  as  a  fulcrum  for  the  entire  dam  is  near  the  top.  To 
overturn  around  such  a  line,  the  dam  must  rupture  on  a  hori- 
zontal plane  passing  entirely  through  the  dam,  the  resistance 
to  which  would  be  very  great  if  the  dam  is  well  built. 

These  considerations  all  add  to  the  security  of  the  dam 
against  overturning  over  that  indicated  by  the  weight  of  the 
masonry  and  the  pressure  of  the  water,  both  of  which  are  definite 
elements,  in  which  the  probable  error  of  calculation  is  small. 

It  is  significant  that  our  records  furnish  no  instance  of  failure 
of  masonry  dams  by  overturning,  while  failures  by  sliding  have 
been  numerous. 


450  MASONRY  DAMS 

6.  Miscellaneous  Forces. — The  above  discussion  considers 
merely  the  water  pressure  in  the  reservoir,  as  resisted  by  the 
weight  of  the  masonry.  There  are  many  other  forces  to  be 
taken  into  account  under  certain  circumstances,  which  may 
be  at  times  of  considerable  importance: 

1.  Ice  pressure. 

2.  Hydrostatic  uplift. 

3.  Wind  pressure. 

In  tropical  and  semitropical  regions,  ice  pressure  need  never 
be  considered,  and  the  same  rule  applies  to  the  southern  tier  of 
States  of  the  United  States.  But  where  winter  extremes  go 
below  zero  Fahrenheit,  and  the  reservoir  is  likely  to  be  full  at 
such  times,  ice  pressure  should  be  considered.  In  some  cases, 
where  reservoirs  are  used  mainly  for  irrigation,  in  cold  or  tem- 
perate regions,  they  are  drawn  down  in  the  autumn  and  cannot 
be  entirely  filled  until  the  snows  melt  in  the  spring,  and  in 
such  cases  ice  pressure  cannot  occur  with  full  reservoir  and  need 
not  be  considered. 

Little  positive  data  is  available  as  to  actual  ice  pressures 
in  large  reservoirs.  Ice  forms  at  temperatures  of  32°  F.  and 
below,  and  contracts  in  volume  as  the  temperature  falls.  If 
this  contraction  produces  cracks,  they  usually  fill  with  water 
which  freezes,  forming  a  solid  mass  again.  When  the  tempera- 
ture rises  the  ice  expands,  and  if  confined  between  rigid  bodies, 
such  as  adjacent  bridge  piers,  may  exert  a  thrust  equal  to  the 
crushing  strength  of  the  ice,  which  may  vary  from  a  small 
amount  to  something  like  800  pounds  per  square  inch.  In  a 
reservoir  with  sloping  sides,  no  such  stresses  can  occur,  and  it  is 
seldom  that  much  allowance  must  be  made  for  this  thrust. 
Local  conditions  should  be  carefully  considered  in  each  case. 

A  precedent  often  quoted  is  a  recommendation  of  a  board 
of  eminent  engineers  that  an  allowance  of  43,000  pounds  per 
linear  foot  be  made  for  ice  pressure  in  the  design  for  the  Quaker 
Bridge  Dam.  No  definite  reason  was  given  for  this  large  allow- 
ance, and  the  precedent  was  not  extensively  followed. 

Ice  pressure  may  be  prevented  by  breaking  or  cutting  it 


MISCELLANEOUS  FORCES  451 

along  the  dam  when  it  forms.  Its  thrust  may  be  minimized 
by  presenting  a  sloping  face  to  the  reservoir  at  the  surface  of 
the  water  when  full. 

a.  Hydrostatic  Uplift. — The  most  important  force  to  be 
considered  and  provided  for  in  addition  to  the  water  pressure 
in  the  reservoir  is  the  buoyant  force  of  water  entering  the 
foundation  or  the  masonry  of  the  dam  under  the  hydrostatic 
head  of  the  reservoir,  with  a  tendency  to  lift  or  float  the 
dam.  Since  most  materials  in  nature  are  not  perfectly  water- 
tight, but  generally  contain  seams  along  which  water  can  travel, 
it  is  practically  impossible  to  exclude  water  entirely  from  the 
foundation.  It  is  almost  equally  difficult  to  construct  masonry 
so  perfect  in  all  its  parts  as  to  entirely  prevent  water  under 
pressure  from  entering  the  structure  to  some  extent.  For  these 
reasons  it  is  necessary  to  make  some  allowance  for  uplift  in  the 
design.  With  the  greatest  practicable  care,  it  is  impossible  to 
determine  in  advance  to  what  extent  uplift  will  take  place 
in  the  completed  structure.  Reasoning  thus,  some  engineers 
have  contended  that  the  only  safe  course  is  to  assume  that  the 
dam  will  be  subjected  throughout  any  horizontal  plane  to  an 
uplift  equal  to  the  entire  hydrostatic  head  corresponding  to 
the  depth  of  water  in  the  reservoir  above  the  surface  of  the  water 
in  the  stream  below,  and  that  the  dam  must  be  made  heavy 
enough  to  be  stable  under  such  conditions.*  If  such  a  cond'tion 
were  possible,  it  would  be  necessary  to  consider  it,  and  to  make 
provision  for  such  part  of  it  as  could  not  with  certainty  be 
prevented  or  overcome. 

The  condition  assumed  cannot  in  fact  exist  or  even  be 
approximated  in  practice.  For  full  hydrostatic  head  to  be 
exerted  upon  an  entire  horizontal  joint,  requires  that  there  be 
no  point  of  contact  between  the  masses  of  rock  or  masonry  above 
and  below  the  plane  or  joint  in  which  such  pressure  occurs.  It 
requires,  moreover,  that  there  be  no  escape  for  the  water  at  the 
lower  face  of  the  dam,  but  that  it  be  absolutely  confined  without 
loss  of  head.  Both  these  conditions  are  practically  impossible 
even  with  the  most  unfavorable  conditions  and  the  poorest 

*  Van  Buren,  Trans.  Am.  Soc.  C.  E.,  Vol.  34,  p.  493. 


452  MASONRY  DAMS 

materials  and  workmanship.  Under  the  worst  conditions  that 
cculd  obtain  in  practice,  actual  contact  would  exist  through 
nearly  one-half  the  area  of  any  horizontal  joint,  and  if  the  struc- 
ture were  reasonably  homogeneous,  it  would  afford  escapes  from 
the  lower  face  of  the  dam  so  abundant  that  though  large  leak- 
age might  occur,  the  hydrostatic  head  would  be  nearly  or  quite 
consumed  in  friction  in  its  passage  through  or  under  the  dam, 
and  could  not  be  in  full  force  throughout  the  joint  as  assumed. 
We  know  from  abundant  experience  that  concrete  can  be 
made  so  nearly  impervious  that  any  leakage  must  be  extremely 
slow  and  through  such  minute  passages  that  any  appreciable 
velocity  of  the  percolating  waters  must  consume  a  large  amount 
of  head  in  friction.  We  also  know  that  many  natural  rocks, 
such  as  limestones,  shales,  and  most  crystalline  rocks,  are  prac- 
tically impervious  except  along  seams,  and  that  the  existence 
of  these  may  be  discovered  and  largely  provided  for. 

As  far  as  the  masonry  is  concerned,  it  is  entirely  possible 
with  proper  design  and  good  workmanship  to  practically  elimi- 
nate internal  water  pressures,  first  by  excluding  the  water 
by  extra  care  in  placing  the  best  selected  materials  used  in  the 
construction  of  the  water  face  of  the  dam,  and  second  by  pro- 
viding an  adequate  drainage  system  just  below  the  water  face 
so  that  any  percolating  waters  may  be  intercepted  and  carried 
away  harmlessly  before  penetrating  any  considerable  distance 
into  the  structure.  Such  provisions  have  been  made  in  many 
recent  high  dams  and  results  show  them  to  be  effective. 

In  the  Arrowrock  Dam  on  the  Boise  River  in  Idaho,  besides 
using  a  rich  mixture  of  Portland  cement  mortar  and  placing  it 
with  special  care  in  the  water  face  of  the  dam,  further  tightness 
was  secured  by  coating  the  surface  of  the  structure  with 
"  gunnite  "  or  the  product  of  the  cement  gun,  projected  with 
great  force  against  the  face  of  the  dam  to  which  it  firmly 
adheres,  and  form.s  a  dense  and  practically  impervious  plaster 
of  cement. 

At  a  distance  of  5  feet  downstream  from  the  upstream  face 
of  the  dam  a  series  of  open  wells  were  built  into  the  masonry, 
at  intervals  of  5  feet  parallel  to  the  axis  of  the  dam,  and  5  feet 


DESIGN  OF  GRAVITY  DAMS  453 

back  of  this  row  another  similar  row  of  wells  was  provided 
with  the  location  of  each  well  staggered  with  reference  to  the 
wells  of  the  first  row.  This  reservoir  has  been  filled  to  overflow 
several  times,  and  each  time  remained  full  or  nearly  full  for 
several  weeks.  In  all  this  time  the  only  leakage  has  been 
through  those  drainage  wells  that  coincide  with  the  contraction 
joints  of  the  dam. 

Similar  provisions  against  uplift  in  the  masonry  have  been 
carried  into  effect  with  complete  success  at  the  Elephant  Butte 
Dam  in  New  Mexico,  and  the  Narrows  Dam  on  the  Yadkin 
River  in  North  Carolina.  At  the  latter  the  water-proof  coating 
was  of  gas  tar  instead  of  gunnite. 

It  is  thus  shown  to  be  entirely  practicable  to  prevent  any  con- 
siderable uplift  in  the  masonry  itself  by  rigidly  providing  certain 
simple  precautions.  To  exclude  such  forces  from  the  foundation, 
however,  is  not  so  easy.  The  precautions  to  be  taken  must 
depend  to  a  large  extent  upon  the  character  of  the  foundation, 
extending  far  below  the  base  of  the  dam  where  detailed  con- 
ditions can  be  only  imperfectly  known.  In  addition  to  these 
precautions  these  dams  were  built  in  vertical  sections  or  columns 
formed  by  providing  joints  or  seams  passing  through  the  dam 
normal  to  its  axis,  and  oiling  these  seams  to  prevent  adhesion 
of  adjacent  sections.  Alternate  sections  were  carried  to  con- 
siderable height  and  allowed  to  season  before  the  intervening 
sections  were  built,  and  the  latter  were  placed  in  cold  weather, 
so  that  in  warm  weather  the  entire  structure  was  placed  in 
compression  by  the  expansion  due  to  temperature. 

Each  of  the  vertical  joints  through  the  dam  was  provided 
with  one  of  the  drainage  wells  above  described,  to  intercept  any 
leakage  due  to  opening  of  the  joint  from  any  cause.  The  pre- 
caution of  building  alternate  sections  in  cold  weather  seems  to 
have  been  effective  in  tightly  closing  these  joints  as  very  little 
leakage  has  been  detected. 

7.  Design  of  Gravity  Dams.— From  the  preceding  pages  it 
appears  that  the  gravity  dam  must  be  so  designed  and  con- 
structed as  to  have  the  following  characters : 

i .  It  must  be  free  from  tension,  especially  on  the  water  face. 


454 


MASONRY  DAMS 


2.  It  must  be  safe  against  sliding  on  any  joint  or  on  foundation. 

3.  It  must  be  safe  against  overturning. 

4.  The  pressures  upon  any  plane  of  the  masonry  or  foundation 
must  be  kept  within  safe  limits. 

5.  The  entrance  of  water  under  pressure  into  the  masonry  or 
foundation  should  be  prevented  as  far  as  possible,  and  where  it 
occurs,  should  be  relieved  by  drainage. 


2%  Core  Hole. 
*-   Grouted. 


FIG.  217. — Section  of  Elephant  Butte  Dam,  Rio  Grande,  N.  M. 


DESIGN  OF  GRAVITY  DAMS 


455 


456  MASONRY  DAMS 

If  the  character  of  the  work  and  the  materials  of  construction 
are  good,  and  the  foundation  is  good  rock,  the  first  three  of  the 
above  requirements  are  generally  met  by  so  designing  the  dam 
that  the  resultant  line  of  pressure  of  all  forces  acting  upon  the 
dam  will,  under  all  conditions,  fall  within  the  middle  third  of  the 
foundation  or  of  any  horizontal  joint. 

If  practicable  it  is  desirable  to  provide  a  spillway  at  such  a 
distance  from  the  dam  as  to  avoid  any  menace  to  the  dam  or  its 
foundations  from  the  energy  of  the  falling  water,  and  avoid  the 
necessity  of  passing  water  over  the  top  of  the  dam.  If  the 
foundation  is  good,  however,  it  is  feasible  to  pass  the  flood  waters 
over  the  top  by  making  suitable  provisions  therefor  in  the 
design. 

Any  mobile  liquid  like  water,  when  free  to  move,  exerts  a 
pressure  at  any  point  which  is  equal  in  all  directions. 

The  pressure  of  a  uniform  column  of  water  upon  a  unit  sur- 
face is  equal  to  the  height  of  the  column  multiplied  by  the 
weight  of  a  unit  volume  of  water.  At  the  surface  of  a  lake  the 
pressure  is  zero.  At  the  depth  of  10  feet  the  pressure  upon  a 
square  inch  surface  is  equal  to  the  weight  of  a  column  of  water 
of  i  inch  cross-sectional  area  and  10  feet  high.  In  other  words, 
the  pressure  of  water  on  a  unit  area  of  a  dam  increases  directly 
as  the  depth,  and  may  be  resisted  by  a  reaction  increasing  in 
like  progression.  It  may  therefore  be  represented  by  a  triangle 
having  its  apex  at  the  surface  of  the  water  and  its  base  in  the 
plane  of  the  bottom  of  the  reservoir. 

Considering  this  triangle  as  made  up  of  a  series  of  horizontal 
courses  of  masonry,  the  width  of  base  of  the  triangle  may  be 
found  by  the  following  formula: 

T-  — 

~W'j 

where   T  =  thickness  in  feet  of  dam  at  a  given  depth ; 
d  =  depth  in  feet ; 

w  =  weight  of  a  cubic  foot  of  water  in  pounds ; 
W  =  weight  of  a  cubic  foot  of  masonry  in  pounds; 
/  =  coefficient  of  friction  of  one  course  of  masonry  upon 
the  course  below  it. 


DESIGN  OF  GRAVITY  DAMS  457 

Taking  the  weight  of  masonry  as  2.3  that  of  water,  and  the 
coefficient  of  friction  as  .6,  we  have  from  the  above  equation,  as  a 
condition  of  equilibrium  so  far  as  sliding  is  concerned, 


A  margin  of  safety  against  sliding  may  be  provided  by 
increasing  the  coefficient  of  d,  and  still  more  by  bonding  the 
dam  firmly  to  its  foundation,  and  building  it  as  a  monolith, 
so  that  it  cannot  slide  without  shearing  the  masonry  of  the 
structure,  or  the  rock  in  its  foundation. 

Reference  is  made  above  to  the  advantage  of  building  a 
gravity  dam  as  a  monolith,  as  this  introduces  a  resistance  to 
shear  that  strengthens  it  against  sliding  on  a  horizontal  joint, 
and  also  against  some  other  methods  of  failure.  There  are 
some  reasons,  however,  for  providing  definite  vertical  joints 
normal  to  the  axis  of  the  dam,  and  these  reasons  have  led  to  the 
adoption  of  such  joints  in  the  design  of  some  of  the  large  masonry 
dams  recently  built.  The  principal  reasons  for  this  provision 
are  two: 

Experience  has  shown  that  any  mass  of  masonry  of  con- 
siderable length  subjected  to  wide  ranges  of  temperature  is 
liable  to  crack  under  the  influence  of  cold,  and  if  built  mono- 
lithic, these  cracks  are  ragged  and  irregular  and  grains  of  sand 
and  mortar  are  loosened  to  be  crushed  when  warm  weather 
closes  the  crack,  and  thus  incipient  disintegration  is  invited. 
They  may  admit  water  to  the  interior  of  the  dam  and  introduce 
internal  pressures  at  points  where  no  provision  has  been  made 
for  taking  care  of  it.  These  troubles  may  be  reduced  by  build- 
ing the  dam  in  separate  sections  with  definite  predetermined 
contraction  joints  normal  to  the  axis  of  the  dam,  which  can 
open  in  cold  weather  without  rupturing  the  masonry,  and  where 
any  leakage  caused  can  be  intercepted  by  drains  provided  in 
advance. 

Another  good  reason  for  providing  such  joints  is  the  advisa- 
bility of  avoiding  any  horizontal  joints.  New  concrete  does 
not  adhere  well  to  that  which  has  been  seasoned  for  some  time. 
When  masonry  work  is  spread  over  a  large  surface  like  the 


458 


MASONRY  DAMS 


§- 


=r, 

s- 
8JI 


DESIGN  OF  GRAVITY  DAMS 


459 


horizontal  section  of  a  large  dam,  where  the  surface  area  may 
reach  20,000  or  30,000  square  feet,  it  is  impossible  to  always 
place  masonry  on  former  work  before  it  has  become  seasoned,— 


Elcv.  3215  ' _j<15-G> 
ff        t 


Spillway 


BOISE  PROJECT   IDAHO 

ARROWROCK   DAM 
MAXIMUM   CROSS  SECTION 


SCALE  OF  FEET 
|    30     20    10      0  20  40  GO 

Xist  of  Drawings 

1  General  map  and  plan  of  construction  work 

2  Maximum  cross  section 

3  Plan  of  dam  and  diversion  works 

4  Elevation  of  developed  upstream  face 

5  Plan  and  section  of  spillwaj 

G  Typical  section  of  diversion  tunnel 

7  Cross  sections  north  wingwalls  at  tunnel 

inlet  and  outlet 

8  Cross  sections  south  wingwalls  at  tunnel 

inlet  and  outlet 

9  Cross  sections  of  cofferdam 


ut  holes  at  10  ft.  erg. 


FIG.  220. — Maximum  Section  of  Arrowrock  Dam. 


in  fact  this  desirable  condition  is  more  likely  to  be  the  exception 
than  the  rule.  If,  however,  the  work  be  confined  within  forms 
bounding  certain  definite  sections  of  limited  area,  this  can  be 
carried  on  at  such  a  rate  that  new  work  can  always  be  placed 


460 


MASONRY  DAMS 


on  previous  work  not  yet  seasoned,  and  good  bond  thus  obtained 
while  work  on  that  section  is  continued.  When  it  becomes 
desirable,  after  several  weeks  or  months  of  concentration  on 
that  section,  to  leave  it  and  go  to  another,  elaborate  pains  can 


be  taken  to  leave  the  surface  in  such  shape  with  projecting 
stones,  etc.,  that  a  good  bond  will  be  obtained  when  work  is 
resumed  at  that  point.  We  thus  secure  greater  immunity  from 
horizontal  joints  by  providing  a  limited  number  of  predeter- 
mined definite  vertical  joints. 


DESIGN  OF  GRAVITY  DAMS  461 

It  is,  however,  important  to  take  precautions  against  the 
liability  of  the  contraction  joints  to  open  in  cold  weather.  To 
prevent  this,  it  is  important  to  carry  the  masonry  up  in  alternate 
columns,  leaving  a  number  of  gaps  in  the  dam  to  be  filled  with 
masonry  after  the  adjacent  columns  have  become  seasoned. 
Considerable  heat  is  generated  in  the  chemical  process  that 
takes  place  in  setting  cement,  and  as  this  stage  passes,  the 
cooling  process  contracts  the  concrete,  producing  a  tendency 
to  crack.  If  the  intermediate  sections  are  postponed  until  this 
contraction  has  taken  place,  and  also  while  the  further  contrac- 
tion of  cold  weather  is  at  or  near  its  maximum,  a  condition  is 
reached  wherein  the  masonry  in  place  is  at  minimum  volume, 
and  by  then  filling  in  between  them  in  late  winter  and  early 
spring,  the  summer  temperature  will  place  the  whole  mass  in 
compression,  and  tend  to  prevent  cracking.  It  is  best  to  make 
the  sections  built  last  much  smaller  than  their  predecessors, 
so  as  to  secure  the  greatest  effect  of  the  precaution  described. 
The  vertical  joints  should  be  designed  with  offsets  so  as  to 
present  a  series  of  right-angled  turns  in  the  path  of  any  leakage 
water  passing  through.  The  joints  should  be  oiled  to  prevent 
adherence,  and  each  joint  should  be  provided  with  a  vertical 
drainage  well  near  the  upstream  face,  to  intercept  any  leakage 
and  conduct  it  to  the  drainage  tunnel.  (See  Fig.  219.)  The 
construction  of  the  dam  in  columns  is  illustrated  by  the  view  of 
Elephant  Butte  Dam,  where  this  was  done.  (See  Fig.  222.) 
This  dam  is  a  demonstration  of  the  success  of  this  measure, 
which  has  had  no  bad  effects,  and  has  reduced  the  leakage  to 
a  very  small  amount. 

The  condition  that  the  line  representing  the  resultant  of 
all  the  forces  acting  upon  the  dam  shall  everywhere  fall  within 
the  middle  third  of  the  cross-section  of  the  dam,  usually  requires 
a  thickness  from  two-thirds  to  three-fourths  of  the  depth  of 
water  to  be  sustained,  depending  upon  the  weight  of  the 
masonry.  This  gives  a  factor  of  safety  of  two  or  more  against 
failure  by  overturning  by  revolving  about  the  lower  toe  as  a 
fulcrum.  As  the  lower  toe  is  an  undulating  line,  rising  to- 
ward both  ends  of  the  dam,  it  cannot  constitute  such  a  fulcrum, 


462 


MASONRY  DAMS 


and  no  part  of  the  dam  can  overturn  without  shearing  the 
masonry  in  one  or  more  planes,  which  gives  a  large  added 
coefficient  of  safety  in  this  respect. 

Pure  theory  of  resistance  of  water  pressure  requires  that 
the  dam  have  a  thickness  of  zero  at  the  highest  water  level. 
To  prevent  overflow  from  wave  action  or  abnormal  rise  of  the 
water  and  as  a  margin  of  safety  it  is  necessary  to  carry  the 


FIG.  222. — Elephant  Butte  Dam,  showing  Construction  in  Alternate  Columns. 

masonry  somewhat  higher,  and  practical  considerations  demand 
an  appreciable  thickness  at  the  top.  It  is  usually  desirable 
to  use  the  top  of  the  dam  as  a  roadway  and  for  this  and  other 
practical  reasons  to  give  it  a  thickness  of  from  10  to  16  feet, 
depending  upon  the  circumstances.  The  water  face  is  usually 
made  vertical  or  nearly  so,  and  the  lower  face  may  also  be 
vertical  down  to  the  plane  where  the  thickness  must  increase 
in  order  to  meet  the  requirement  that  the  resultant  of  forces 
fall  within  the  middle  third.  This  is  secured  in  the  average 


DESIGN  OF  GRAVITY  DAMS 


463 


case  by  sloping  the  downstream  face  on  a  slope  of  about  3 
horizontal  to  4  vertical,  varying,  however,  with  the  weight  of 
the  masonry.  These  slopes  may  continue  downward  from  the 
top  to  the  point  where  the  pressure  on  foundation  at  the  lower 
toe,  reservoir  full,  and  on  the  heel,  reservoir  empty,  reaches 
the  safe  limit  of  pressure  either  upon  masonry  or  upon  foundation. 


Rubble 
Concrete 


Scale,  1  inch  =50  feet 
FIG.  223. — Cross-section  of  Periar  Dam,  India. 

At  this  point  the  slope  of  the  lower  face  must  be  increased  to 
about  i  on  i,  to  prevent  increase  of  unit  pressures,  reservoir  full. 
To  prevent  increase  of  pressure  on  the  heel  a  slope  of  the  upper 
face  must  be  adopted,  which  will  increase  the  bearing  surface  as 
fast  or  faster  than  the  vertical  pressure. 

It  is  sufficient,  as  a  rough  rule,  to  begin  the  batter  just  above 


464 


MASONRY  DAMS 


the  point  where  the  limit  of  pressure  is  reached,  and  carry  it 
down  on  a  ratio  of  i  horizontal  to  10  vertical. 

It  is  reasonable  and  logical  to  assume  a  higher  limit  of  safe 
pressure  at  the  heel  of  the  dam  than  at  the  toe,  because  the  for- 
mer limits  can  be  reached  only  when  the  reservoir  is  entirely 
empty,  which  will  seldom  occur  in  practice,  and  a  failure  at 
that  time  will  affect  only  the  structure  itself,  without  menace 
to  human  life  or  to  other  property  than  the  dam. 


Riveriftd 


FIG.  224. — Cross-section  of  Masonry  Dam,  New  Croton  Dam,  Cornell's. 

On  the  other  hand  the  pressures  on  the  toe  reach  their  maxi- 
mum only  when  the  reservoir  is  full,  which  is  supposed  to  happen 
frequently,  and  failure  under  such  circumstances  would  entail 
awful  havoc,  devastation,  and  loss  of  life.  Such  possibilities 
always  -demand  much  higher  factors  of  safety  than  cases  where 
such  vast  risks  of  life  and  property  are  not  involved. 

The  primary  reason  for  the  requirement  that  the  resultant  of 


DESIGN  OF  GRAVITY  DAMS  465 

forces  always  fall  within  the  middle  third  is  the  desirability  of 
avoiding  any  tensile  stresses  in  the  masonry.  This  is  far  more 
important  on  the  water  face  of  the  dam  than  on  the  down- 
stream face.  If  the  resultant  of  forces,  reservoir  full,  falls  with- 
out the  middle  third,  it  tends  to  produce  tension  on  the  water 
face.  This  is  extremely  undesirable,  as  it  tends  to  open  cracks 
in  the  masonry  at  times  when  water  under  pressure  is  ready  to 
enter  such  cracks  and  exert  a  pressure  tending  both  to  over- 
turn the  dam  and  to  cause  sliding,  at  the  time  when  failure 
would  be  most  disastrous.  At  the  same  time  the  requirement 
in  question  gives  us  a  margin  of  safety  against  overturning. 

The  avoidance  of  tension  on  the  water  face  of  the  dam  or 
foundation  is  so  important  that  the  resultant  of  pressure,  reser- 
voir full,  should  be  kept  sufficiently  inside  the  middle  third  to 
amply  cover  any  errors  that  can  occur  in  the  assumed  weight  of 
masonry,  force  of  wind  and  waves,  ice  thrust,  or  extreme  height 
of  water  in  the  reservoir. 

Should  the  resultant  fall  outside  the  middle  third,  reservoir 
empty,  it  will  tend  to  produce  tension  on  the  downstream  slope 
of  the  dam,  which  is  theoretically  undesirable,  but  not  nearly 
so  important  as  if  it  occurred  on  the  other  side,  first,  because 
there  is  no  water  to  enter  the  masonry  on  the  downstream  slope, 
and  second,  because  it  occurs  with  reservoir  empty,  when  there 
is  no  real  danger  of  failure,  and  no  life  or  property  menaced 
thereby.  On  the  other  hand  the  tension  that  theoretically  begins 
as  the  resultant  passes  from  the  middle  to  the  outer  third,  is 
based  on  the  assumption  that  the  masonry  is  rigid  and  inelastic. 
Any  elastic  yield  will  tend  to  modify  the  theory,  and  slightly 
shift  the  point  at  which  the  tension  begins.  Moreover,  well- 
built  masonry  will  stand  some  tension  and  good  practice  some- 
times allows  a  tensile  stress  in  concrete  of  50  pounds  per  square 
inch.  Standard  specifications  require  a  strength  of  150  pounds 
per  square  inch  at  thirty  days,  for  Portland  cement  mortar,  and 
good  cement  will  greatly  increase  this  with  further  age. 

Any  tendency  of  the  resultant  to  fall  outside  of  the  middle 
third  on  the  water  side,  reservoir  empty,  is  necessarily  accom- 
panied by  greater  vertical  pressure  at  and  near  the  water  face, 


466 


MASONRY  DAMS 


DESIGN  OF  GRAVITY  DAMS 


467 


FIG.  226. — Plan  of  Roosevelt  Dam,  Arizona. 


468 


MASONRY  DAMS 


-158  feet- 
Scale  of  Feet 

0        10        20       30       40        50 

FIG.  227. — Maximum  Cross-section,  Roosevelt  Dam,  Arizona. 


DESIGN  OF  ARCH  DAMS  469 

and  this  tends  at  all  stages  of  the  reservoir  to  close  and  keep 
closed  possible  horizontal  openings,  and  thus  to  exclude  water 
from  the  masonry.  There  is,  of  course,  no  danger  of  the  dam 
overturning  toward  the  reservoir  when  it  is  empty. 

It  is  thus  seen  that  there  is  no  valid  objection  to  allowing 
the  resultant  of  pressure,  reservoir  empty,  to  fall  slightly  out- 
side the  middle  third,  so  long  as  the  actual  pressures  on  masonry 
are  kept  within  safe  limits. 

8.  Design  of  Arch  Dams.  —  As  pointed  out  on  page  449 
any  masonry  dam  can  be  made  more  secure  against  sliding  and 
overturning  than  it  would  otherwise  be  by  building  it  on  a 
curved  plan,  convex  upstream.  This  makes  it  impossible  for 
the  dam  to  yield  to  the  water  pressure,  without  crushing  the 
masonry  or  abutments,  thus  utilizing  forces  not  brought  into 
play  by  its  resistance  simply  as  a  gravity  structure. 

Navier's  formula  for  computing  water  stresses  on  the  vois- 
soirs  of  an  arch  is  as  follows: 


Where  Q  =  the  compressive  stress  upon  any  strip  of  unit  width 

extending  through  the  dam,  at  any  given  depth; 
P  =  horizontal  pressure  on  unit  surface  at  the  same  depth  ; 
R  =  radius  of  the  curve  of  the  extrados  of  the  arch. 

This  value  is  based  entirely  on  the  assumption  that  all  the 
pressure  is  sustained  by  the  arch.  It  shows  that  the  pressure 
is  inversely  as  the  length  of  the  radius,  and  therefore  the  longer 
the  radius  the  greater  the  pressure,  and  the  thicker  must  be 
the  dam  section. 

As  we  shorten  the  radius  we  reduce  the  stresses  and  thus 
permit  reduction  of  the  thickness  of  the  dam,  but  at  the  same 
time  we  have  increased  its  length.  Jorgenson  has  shown  that 
the  gain  exceeds  the  loss  in  a  decreasing  amount  until  we  have 
a  radius  equal  to  less  than  five-ninths  of  the  width  of  the  canyon 
at  the  dam  site,  shortly  after  which  the  balance  gradually  shifts 
the  other  way.  This  gives  an  arc  of  a  little  over  133  degrees. 
The  theoretical  advantage  in  using  so  long  an  arc,  or  in  other 


470 


MASONRY  DAMS 


FIG.  228. — Pathfinder  Dam,  North  Platte  River,  Wyoming.    Lower  face  showing 
concrete  ladder,  and  6500  second-feet  of  water  discharging  from  tunnel. 


DESIGN  OF  ARCH  DAMS 


471 


472 


MASONRY  DAMS 


words,  so  short  a  radius  over  that  of  a  somewhat  longer  radius 
is  small,  as  the  diminished  thickness  of  the  dam  tends  to  diminish 
its  resistance  as  a  cantilever,  and  increase  its  susceptibility  to 
vibration.  In  practice,  therefore,  it  is  desirable  to  make  the 
included  angle  about  120  degrees  if  the  physical  conformation 
of  the  dam  site  is  suitable. 


SECTION  A-B  SECTION  C-D 

FIG.  230. — Meer  Allum  Dam,  India.     Plan  and  Section  of  One  Arch. 

All  dam  sites  are  wider  at  top  than  at  bottom,  and  most  of 
them  have  a  shape  somewhat  resembling  the  letter  V.  It 
follows,  therefore,  that  to  obtain  the  greatest  practical  benefit 
from  the  arch  action  it  becomes  necessary  to  vary  the  radius 
from  a  very  short  one  near  the  bottom,  to  a  longer  one  at  the  top. 

This  design  of  dam  has  been  called  the  "  variable  radius  " 
dam,  or  more  often  the  "  constant  angle  "  dam,  and  has  been 
patented  by  F.  G.  Baum  &  Company,  of  San  Francisco,  Cali- 
fornia. The  Salmon  River  Dam  near  Juneau,  Alaska,  has  been 


DESIGN  OF  ARCH  DAMS 


473 


built  on  this  principle,  and  to  a  less  degree  of  exactness,  the 
Lake  Spaulding  Dam  on  the  South  Yuba  River  in  California. 

The  most  convenient  and  clearest  expression  is  to  state  the 
curvature  in  terms  of  the  radius,  and  this  in  terms  of  the  width 
of  the  canyon,  or  in  other  words 
the  chord  of  the  angle. 

A  rough  rule  for  the  change 
of  curvature  in  an  arch  dam 
which  secures  the  benefit  of  the 
variable  principle  and  gives 
due  weight  to  practical  con- 
siderations, is  to  begin  at  the 
bottom  with  a  radius  of  about 
three-quarters  of  the  chord  at 
that  level,  and  change  this 

radius  gradually  and  uniformly  i-.20'-- 

toward  the  top,  ending  at  the         FIG.  231.— Cross-section  of  Bear 

top  with    a   radius    nearly  five-  Valley  Dam,  California. 

ninths  the  length  of  the  chord  at  that  level.  This  will  vary 
the  subtended  angle  from  about  84  degrees  at  the  bottom  to 
about  120  degrees  at  the  top.  It  will  secure  the  benefit  of 
cantilever  action  near  the  bottom  where  most  important  and 


FIG.  232.— Plan  and  Elevation  of  Bear  Valley  Dam,  California. 


avoid  most  of  the  practical  difficulties  of  construction  involved 
in  a  too  rigid  adherence  to  a  constant  angle. 

In  many  cases  a  dam  site  widens  rapidly  near  the  top,  and 
becomes  too  wide  to  be  closed  by  a  dam  acting  as  an  arch, 


474 


MASONRY  DAMS 


while  the  lower  part  of  the  site  is  well  adapted  to  such  an  arch 
design.  In  such  a  case,  it  is  often  possible  to  build  masonry 
abutments  as  gravity  structures  of  moderate  height,  and  thus 


-•-=^--891—-    r--SI 881 9 


make  a  necessary  span  for  the  arch,  of  400  or  500  feet,  well- 
adapted  to  closure  by  an  arch.  The  artificial  abutments  become 
simply  tangential  continuations  of  the  arch.  They  are  straight 
gravity  dams,  and  receive  endwise  the  thrust  of  the  arch. 


MASONRY  OVERFALL  DAMS 


475 


9.  Masonry  Overfall  Dams. — Where  it  is  intended  that 
water  shall  flow  over  the  top  of  a  dam  the  prevailing  practice 
is  to  give  the  top  and  lower  slope  a  compound  curve,  such  that 
the  water  in  flowing  over  will  everywhere  rest  upon  masonry 
and  not  leave  a  vacuum  behind  the  sheet  of  falling  water,  and 
so  that  the  water  will  be  guided  into  a  horizontal  direction  as 
it  leaves  the  dam. 

Where  water  falls,  as  in  flowing  over  a  dam  a  quantity  of 
energy  is  generated,  equal  to  the  weight  of  the  falling  water 


El.   100.2' 


FIG.  234. — Cross-section  of  New  Holyoke  Weir,  Mass. 

multiplied  by  the  height  of  the  fall.  This  energy  must  some- 
how be  dissipated  in  friction  either  in  its  own  mass,  or  upon 
its  channel.  Different  engineers  hold  different  theories  con- 
cerning the  best  method  for  preventing  this  energy  from  destroy- 
ing or  injuring  the  dam.  One  method  is  to  dissipate  the  energy 
as  soon  as  possible  at  the  time  and  place  of  its  generation.  To 
this  end  the  water  is  made  to  fall  as  nearly  vertically  as  possible 
upon  steps  or  shelves  of  masonry  on  the  lower  side  of  the  dam, 
and  finally  into  a  pool  or  water  cushion  at  the  toe  of  the  dam, 


476 


MASONRY  DAMS 


El.  1310 


where  the  desired  end  is  accomplished  by  impact  and  friction 
upon  the  masonry  and  upon  the  bottom  and  sides  of  the  pool, 
and  by  the  lashing  and  churning  of  the  water  in  its  own  mass. 
It  is  caused  to  emerge  quietly  from  the  pool  at  moderate  veloci- 
ties that  will  not  erode  the  channel  below.  This  method,  of 
course,  requires  the  best  of  massive  construction  to  prevent 
damage  at  the  points  of  impact  and  erosion,  and  it  is  usually 

necessary  to  protect  the  river 
banks  for  some .  distance  be- 
low, from  erosion  by  the 
waves  of  the  agitated  water 
as  it  leaves  the  vicinity  of 
the  dam. 

The  other  method  is  to 
guide  the  water  down  the 
lower  slope  of  the  dam  and 
gently  deflect  it  to  a  hori- 
zontal direction,  disturbing 
its  velocity  as  little  as  pos- 
sible, and  leading  it  as  far 
as  possible  from  the  dam 
before  much  of  its  energy  is 
dissipated.  The  object  is  to 
cause  the  water  to  expend 
its  stored  energy  in  over- 
coming the  friction  of  the 
river  ^bed  at  some  distance 
from  the  dam,  instead  of 
on  the  dam  itself.  This 
method  also  requires  protection  of  the  river  banks  from  erosion 
for  a  considerable  distance  below,  unless  they  are  naturally 
composed  of  good  rock. 

Where  this  method  is  adopted,  the  water  falling  over  the  dam 
arrives  at  the  toe  with  a  very  high  velocity,  which  is  that  of  a 
body  falling  through  the  same  height  under  the  action  of  gravity, 
minus  the  friction  losses  upon  the  dam  and  the  air.  If  the 
vertical  motion  is  changed  by  the  curves  of  the  masonry,  very 


•   Katural  ground  «*  «,«»»/,,;, 

rock  Cll  f,./]1 

rods,  3-o'long,  grouted  C        L'lf 
WA«  J 


SECTION  EJED  ROCK 
ELEVATIONS  1275-1284 


FIG.  235. — Cross-section  of  Granite  Reefs 
Weir,  Salt  River,  Arizona. 


MASONRY  OVERFALL  DAMS 


477 


gently,  to  a  horizontal  direction,  it  will  retain  nearly  the  same 
velocity  and  flow  away  from  the  dam  at  that  rate  for  a  short 
distance,  and  suddenly,  and  with  great  commotion  check  its 
velocity,  and  increase  its  depth  in  proportion.  This  is  called 
the  "  hydraulic  jump."  Where  this  change,  and  the  correspond- 
ing commotion  occurs,  a  great  deal  of  work  is  done  by  the  water 
upon  its  own  mass  and  upon  its  channel,  the  work  being  sufficient 
to  absorb  the  difference  in  energy  between  the  velocity  above  and 
below  the  hydraulic  jump.  If  the  channel  at  this  point  is  too 
soft  or  friable  to  resist  this  violent  action,  it  must  be  well  pro- 
tected, or  measures  must  be  adopted  to  check  the  velocity  and 
dissipate  the  energy  nearer  the  dam.  This  latter  alternative 


FIG.  236. — Cross-section  of  Norwich  Water  Power  Company's  Weir. 

was  adopted  at  the  spillway  of  the  Gatun  Dam  on  the  Canal 
Zone,  and  at  the  Bassano  overflow  dam  in  Alberta,  Canada. 

At  Gatun,  two  rows  of  staggered  rectangular  baffle  piers 
of  concrete  were  placed  near  the  toe  of  the  dam  to  intercept 
the  swift  water,  deflect  parts  of  the  stream  upon  other  parts, 
and  thus  destroy  the  major  portion  of  the  energy  stored  in  the 
swift  water.  The  object  was  attained,  but  the -impact  of  the 
water  upon  the  baffle  piers  was  so  destructive  that  it  was  nec- 
cessary  to  protect  them  with  heavy  cast-iron  plates  to  receive 
the  shock.  This  provision  has  accomplished  the  purpose. 

The  Bassano  Dam  is  equipped  with  two  staggered  rows  of 
"  baffle  piers,"  shaped  like  snowplows  pointed  upstream,  and 
designed  to  split  up  the  high-velocity  sheet  of  water  before  it 


478 


MASONRY  DAMS 


can  strike  the  bed  of  the  stream,  and  throw  one  jet  against 

another   so   that   the 
energy  will    be     ab- 
sorbed   as    much    as 
possible     by     eddies 
within    the    body  of 
the  downstream  pool, 
and    not    by   tearing 
the  foundations.    The 
^    baffle    piers    are    not 
£    designed    to    destroy 
tf   the  energy  by  impact, 
'2    but  to  start  eddies  in 
<u    the  water,  and  insure 

T3 

§  the  start  of  the  hy- 

^  draulic  jump  at  the 

&  toe  of   the    dam,    so 

•55  that  its  stored  energy 

^  will      be      dissipated 

•|  before    it   leaves   the 

.>  concrete  apron. 

Q 

^         10.  Hollow    Con- 
£    crete  Dams. — An  in- 

KS 

troduction  of  com- 
I.  paratively  recent 
«*  years,  is  a  variety  of 
8  hollow  or  cellular 

pU| 

dams,  built  of  rein- 
forced concrete. 
These  are  develop- 
ments of  the  timber 
dams  built  with 
rather  flat  water 
slopes,  so  as  to  in- 
troduce a  vertical 
component  of  water  pressure,  tending  to  give  weight  to 
the  dam  and  hold  it  in  place.  The  corresponding  concrete 


HOLLOW  CONCRETE  DAMS 


479 


480 


MASONRY  DAMS 


type  consists  of  a  series  of  buttresses,  supporting  a  sloping  deck 
composed  of  reinforced  concrete  slabs.     A  modification  of  this 


This  Furring  Piece  to  to' 
1,12  Ej  15  Ibs.  with  Back; 


SIDE  ELEVATION 


FIG.  239. — Steel  Forms.     McCall's  Ferry  Dam,  Susquehanna  River,  Penn. 

type  employs  arches  of  plain  concrete  instead  of  reinforced 
slabs  to  close  the  gaps  between  buttresses.  This  is  called  the 
multiple  arch  type  of  dam.  In  favor  of  this  type  is  the  fact  that 


FIG.  240. — Cross-section  of  La  Grange  Dam,  California. 

it  does  not  require  reinforcement,  which  in  time  might  corrode, 
but  this  is  met  by  the  argument  that  in  the  case  of  the  multiple 
arch  dam,  the  failure  of  one  arch  would  remove  the  support 


HOLLOW  CONCRETE  DAMS 


481 


1 


482 


MASONRY  DAMS 


FIG.  242. — East  Park  Reservoir  Spillway,  Orland  Project. 


FIG.  243.— Diversion  Dam,  East  Park  Feed  Canal,  Orland  Project. 


HOLLOW  CONCRETE  DAMS 


483 


I 


484  MASONRY  DAMS 

.from  its  buttresses,  and  cause  them  to  fail  under  the  lateral 
thrust  of  the  adjacent  arches,  thus  causing  the  failure  of  all 
the  arches  in  succession.  This  objection  to  the  multiple  arch 
type  can  be  overcome  in  various  ways. 

The  most  obvious  way,  and  the  one  usually  relied  upon,  is  to 
build  each  arch  so  conservatively  that  it  will  not  fail,  and  the 
side  thrusts  will  balance.  Another  method  is'  to  eliminate 
the  side  thrust.  If  each  arch  is  made  nearly  a  half  circle,  the 
buttresses  can  be  each  made  to  take  the  thrust  of  either  arch 
independent  of  any  support  from  the  adjacent  arch.  A  third 
method  is  to  tie  adjacent  buttresses  together  at  the  springing 
of  the  arches,  with  beams  to  take  either  compression  or  tension, 
thus  making  each  buttress  sustain  its  neighbor. 

Jorgensen  has  shown  that  the  angle  of  arch  requiring  the 
least  quantity  of  concrete  is  133^  degrees,  but  that  one  having 
a  longer  radius,  and  subtending  only  120  degrees,  contains 
for  the  same  stresses  only  i  per  cent  more  concrete,  but  gives 
6  per  cent  greater  thickness.  As  this  requires  less  forming, 
and  less  labor  in  placing,  it  is  somewhat  cheaper,  besides  offering 
greater  resistance  to  percolation  of  water,  and  is  therefore 
preferable. 

Similarly  very  short  spans,  with  small  buttresses  close 
together,  require  theoretically  less  concrete  than  longer  ones, 
but  thin  buttresses  and  arches,  especially  if  high,  are  more  likely 
to  collapse,  require  more  forming  and  labor  in  placing,  and  the 
arches  are  more  likely  to  permit  the  passage  of  water.  These 
practical  reasons  indicate  spans  of  40  to  50  feet,  depending 
upon  the  height.  With  buttresses  40  feet  from  center  to  center, 
a  radius  for  the  upstream  face  of  23.1  feet  will  give  an  arc  of 
about  120  degrees,  and  make  economical  construction. 

Cellular  concrete  dams  of  either  type,  if  low,  require  much 
less  cement  than  the  ordinary  gravity  type.  This  advantage 
grows  less  as  the  height  increases  up  to  heights  of  about  120 
feet,  above  which,  owing  to  increased  thickness  of  buttresses 
and  arch  rings  and  necessary  bracing  the  advantage  soon  dis- 
appears. The  cost  of  steel  reinforcement  if  used,  and  of  forms, 
tends  to  counter  balance  any  advantage  in  cement,  and  each 


HOLLOW  CONCRETE  DAMS 


485 


case    must    be    carefully    considered    in    the    light    of    local 
conditions. 

A  unique  buttressed  dam  of  reinforced  concrete  has  been 
built  by  the  Reclamation  Service  to  close  East  Park  reservoir, 
Orland  project,  California.  This  dam,  which  acts  as  a  spillway 
in  flood,  is  but  n  feet  high  and  consists  of  a  number  of  circular 


Expansion 
Joint 


Maximum  high 
water  El.  188.7 


*  Cut  off  wall 
1 18"  Wide,  to  be 


FIG.  245.  —  East  Park  Multiple  Arch  Spillway,  Orland  Project,  California. 


walls  of  13!  feet  radius,  convex  upstream  and  sustained  by 
concrete  buttresses  of  8  feet  thickness,  sloping  downstream 
with  gradient  of  ij  to  i. 

These  walls  (Fig.  245)  are  of  reinforced  concrete  18  inches 
thick,  resting  on  a  floor  12  inches  thick,  and  below  the  walls  and 
between  the  buttresses  are  subsidiary  wails  2  feet  high  forming 


486 


MASONRY  DAMS 


water-cushions.     Downstream    is    a   concrete    apron   8    inches 
thick  extending  for  a  distance  of  30  feet. 

An  important  advantage  of  any  hollow  type  of  dam  is  the 
fact  that  the  pressures  on  foundation  can  be  limited  to  a  small 


FIG.  .246.— Cross-section  of  Iron  Weir,  Cohoes,  N.  Y. 

amount  by  spreading  the  base  of  the  dam  as  desired  and  dis- 
tributing the  pressure  nearly  equally  over  it.  For  this  reason 
foundations  of  soft  rock,  clay,  or  shale  can  be  utilized  with  a 
much  higher  factor  of  safety  than  possible  with  a  gravity  dam. 


£  Rods 


FIG.  247. — Cross-section  of  Reinforced  Concrete  Weir,  Theresa,  N.  Y. 

This  possibility  seems  to  have  led  to  the  careless  preparation 
of  foundations  in  some  cases,  and  two  failures  of  such  dams 
have  occurred,  due  to  erosion  of  foundations  bv  water  under 


STEEL  DAMS  487 

pressure,  in  regard  to  which  the  hollow  dam  has  no  advantage 
over  the  gravity  type.  Percolation  under  the  dam  must  be 
prevented  by  a  cut-off  wall  carried  down  to  rock  and  also  by 
grouting  the  seams  of  the  rock  if  there  is  any  probability  of 
erosion  by  percolating  waters  under  pressure.  In  short,  the 
foundation  should  be  prepared  for  a  hollow  dam  very  much  as 
for  a  solid  dam. 

ii.  Steel  Dams. — Hollow  or  cellular  dams,  built  first  of 
wood,  and  later  of  concrete,  may  also  be  constructed  of  steel, 
and  several  dams  of  this  type  have  been  actually  built.  A 
sloping  water-face  is  supported  by  a  steel  frame  of  standard 
shapes  taking  the  water  pressure  mainly  in  compression.  The 
water-face  is  a  deck  of  steel  plates,  which,  instead  of  being  in 
the  form  of  arches  as  in  the  multiple  arch  dam,  or  of  beams 
as  in  the  Ambursen  type,  are  placed  in  the  form  of  half -cylinders, 
concave  upward  toward  the  reservoir,  so  that  the  pressure  of 
the  water  places  the  plates  in  tension. 

Such  dams  are  comparatively  cheap,  and  if  properly  pro- 
tected from  corrosion  should  have  long  life. 

A  steel  dam  on  the  Missouri  River  failed,  and  was  replaced 
by  a  masonry  structure,  but  the  failure  was  of  the  foundation 
and  not  due  to  the  type  of  dam  employed. 

a.  Steel  Dam,  Ash  Fork,  Arizona. — This  structure,  built 
wholly  of  metal  and  intended  for  the  impounding  of  water,  was 
built  by  the  Santa  Fe  railway  to  store  water  for  use  of  locomotives 
and  for  city  supply,  and  has  a  capacity  of  no  acre-feet. 

The  Ash  Fork  dam  is  184  feet  long  on  top,  and  about  300  feet 
in  total  length,  including  a  short  concrete  abutment  at  each  end. 
Its  greatest  height  is  46  feet.  Structurally  it  consists  of  a  series 
of  triangular  steel  bents  or  frames,  resting  on  concrete  founda- 
tions and  carrying  steel  face-plates  on  the  inclined,  or  upstream 
face  of  the  bents.  The  foundations  of  the  steel  bents  are  of 
Portland-cement  concrete  and  the  vertical  posts  rest  on  concrete 
walls  (Fig.  248). 

There  are  24  bents,  each  a  right-angled  triangle,  with  the 
inclined  side  having  a  slope  of  45  degrees,  facing  upstream,  the 
rocky  bottom  of  the  canyon  forming  the  base.  The  dimensions 


488 


MASONRY  DAMS 


of  the  bents  vary  with  their  height.  The  end  bents  (Nos.  i  to  7 
and  No.  24)  are  12  to  21  feet  in  height,  each  consisting  of  a  verti- 
cal Z-bar  column  and  an  inclined  I-beam.  Bents  Nos.  8,  9,  22, 
and  23,  are  about  33  feet  high.  Each  has  a  vertical  Z-bar 
column,  an  inclined  I-beam,  and  two  inclined  posts  or  columns 
built  up  of  Z-bars,  the  upper  of  these  resting  on  the  same  shoe 
or  bed-plate  as  the  vertical  post.  Bents  Nos.  10,  n,  12,  19,  20, 
and  21  are  33  feet  to  41  feet  10  inches  high.  These  have  but 
one  inclined  post,  which  rests  on  the  same  bed-plate  as  the  verti- 
cal post  while  above  it  are  truss  members  connecting  the  face 


FIG.  248. — Steel  Dam,  Ash  Fork,  Arizona. 

member  with  the  posts.  Bents  Nos.  13  to  18,  inclusive,  are  36 
feet  to  41  feet  10  inches  high,  and  have  two  inclined  posts, 
with  truss  members  above  the  upper  post.  In  all  of  them  the 
face  is  composed  of  a  20-inch  65-pound  I-beam,  reinforced 
on  the  underside  by  a  plate  J  inch  thick  and  18  inches  wide. 
The  vertical  and  inclined  posts  are  all  composed  of  four  Z-bars 
and  a  web-plate.  The  bents  are  connected  by  four  sets  of 
transverse  diagonal  bracing  between  the  vertical  and  inclined 
posts  The  bracing  is  composed  of  single  or  double  angle- 
irons,  1X3X3  inches,  the  ends  of  which  are  riveted  to  connection- 
plates. 


STEEL  DAMS 


489 


j 

I  ili«M:d  i/<5 


490  MASONRY  DAMS 

The  structure  is  composed  of  alternate  rigid  and  loose  panels. 
The  crest  or  apron-plates  which  fit  the  braced  panels  between  the 
bents  are  riveted  to  a  curved  angle,  which  is  riveted  to  the  upper 
end  of  the  curved-plate,  while  in  the  unbraced  panels  this  curved 
angle  merely  bears  on  the  apron-plate.  The  face  of  the  dam 
is  composed  of  steel  plates  f  inch  thick  and  8  feet  lof  inches 
wide  and  8  feet  long,  riveted  to  the  outer  flanges  of  the  I-beams 
of  the  bents.  They  are  curved  transversely  to  a  radius  of  7  feet 
6  inches,  forming  a  series  of  gullies  or  channels  down  the  face, 
the  widths  of  the  channels  being  7  feet  5  inches  measured  on  the 
chord,  leaving  at  each  side  a  flat  portion  which  rests  on  and  is 
riveted  to  the  I-beams.  There  are  seven  expansion  rivets  at 
intervals  of  about  five  bents,  and  all  joints  exposed  to  water- 
pressure  are  well  caulked. 

A  weakness  of  the  structure  is  that  the  masonry  foundations 
were  not  carried  down  to  impervious  rock,  and  in  consequence 
the  dam  at  first  failed  to  serve  its  purpose,  much  of  the  water 
impounded  being  passed  under  and  around  it  by  seepage  through 
the  permeable  loose  rock  and  volcanic  cinder  foundation  material. 
Later  concrete  was  used  to  connect  the  steel  facing  with  the  rock 
foundations,  and  this  was  covered  with  asphaltum  and  is  reported 
to  have  greatly  reduced  the  leakage. 

12.  Foundations  of  Masonry  Dams. — The  foundation  of  a 
masonry  dam,  especially  a  high  dam,  is  an  element  of  first 
importance.  The  structure  should,  if  possible,  rest  upon  rock, 
which  must  be  of  such  hardness  and  strength  as  to  resist  the 
pressures  to  be  applied.  For  dams  not  exceeding  50  feet  in 
height,  foundation  of  clay  or  gravel  may  be  made  to  answer 
with  proper  cut-off  provisions.  If  of  clay,  sand,  or  fine  gravel, 
or  any  material  into  which  piling  can  be  driven,  the  weight 
should  be  carried  on  piles,  providing  a  liberal  coefficient  of 
safety. 

The  foundation  must  in  any  case  be  practically  impervious, 
so  as  to  allow  no  water  to  flow  through  under  such  pressure  as 
to  cause  erosion,  and  so  undermine  the  dam.  The  exclusion 
from  the  foundation  of  water  under  pressure  is  important, 
also,  for  another  reason.  If  water  can  enter  the  foundation 


FOUNDATIONS  OF  MASONRY  DAMS  491 

from  the  reservoir,  and  has  not  free  exit,  it  produces  a  hydro- 
static pressure  under  the  dam  tending  to  lift  or  float  it,  and 
unless  large  provision  is  made  for  this  in  the  design,  it  may 
cause  failure.  We  have  already  seen  the  importance  of  pre- 
venting tension  in  the  masonry  of  the  upstream  face  of  the  dam 
because  of  its  tendency  to  admit  water  under  pressure  into  the 
masonry,  and  thus  produce  uplift. 

The  method  of  failure  of  masonry  dams  most  common  is 
by  sliding  on  foundation.  This  has  occurred  in  at  least  two 
notorious  cases  in  America,  accompanied  by  loss  of  life  and 
property.  These  were  both  undoubtedly  caused  by  uplift 
of  water  in  the  foundations. 

In  each  case  the  dam  was  founded  on  horizontally  stratified 
rock,  the  bedding  seams  of  which  were  filled  with  clay  or  other 
soft  material  with  little  cohesion,  and  serving  as  a  lubricant 
when  wet.  Such  foundation  also  affords  maximum  facilities 
for  the  entrance  of  water  under  the  dam  and  the  exercise  of 
upward  pressure  upon  the  dam,  thus  neutralizing  part  of  its 
weight,  and  inducing  failure  for  lack  of  effective  weight. 

The  determination  of  the  perviousness  of  natural  formations 
is  very  difficult,  as  any  examination  which  disturbs  them  changes 
the  conditions  it  is  desired  to  know. 

In  general,  it  may  be  said  that  water  will  more  readily 
traverse  seams  in  rock  or  bedding  planes  than  devious  paths 
through  the  material  of  the  rock.  It  follows  that  it  will  generally 
pass  more  readily  and  in  larger  volume  in  the  direction  of  strati- 
fication, than  in  any  other  direction.  Similarly  stratified  rock 
will  permit  percolation  more  easily  and  in  greater  volume 
than  good  massive  rock,  such  as  granite. 

Granular  rock,  such  as  sandstone,  is  likely  to  transmit  more 
water  through  the  rock  itself  than  one  of  finer  grain  or  denser 
structure,  like  shale  or  limestone.  Meyer  states  ("  Hydrology  " 
page  264),  that  granitic  rocks  usually  contain  less  than  i  per 
cent  of  voids,  limestone  i  to  5  per  cent,  and  sandstone  6  to  25 
per  cent.  The  percentages  of  voids  in  clay  and  shale  are  greater, 
but  the  grains  and  the  voids  between  them  are  so  small  that  water 
moves  through  them  with  extreme  difficulty  and  slowness. 


492  MASONRY  DAMS 

No  exact  rules  of  this  nature  can  be  laid  down,  because  there 
are  many  varieties  of  each  kind  of  rock,  with  different  percolating 
capacities.  In  general,  however,  the  following  rules  may  be 
taken  as  rough  guides: 

1.  Massive  or  crystalline  rocks  such  as  granite  gneiss  and 
schists  will  transmit  water  less  freely  than  sedimentary  rocks. 

2.  Stratified  rocks  will  transmit  water  more  readily  in  the 
direction  of  stratification  than  transverse  thereto. 

3.  In  the  direction  normal  to  stratification,  sandstone  will 
generally  transmit  water  more  readily  than  limestone  or  shale. 

4.  Stratification  on  a  plane  approximately  horizontal  is  the 
worst  condition   for   introducing  upward  pressures  beneath   a 
dam.     Conversely,  the  most  favorable  position  in  this  respect 
for  stratified  rock  is  in  nearly  vertical  beds. 

As  all  rock  contains  some  seams,  and  nearly  all  rock  is  more 
or  less  pervious,  it  is  unsafe  to  assume  that  any  foundation  is 
entirely  impervious.  It  follows  that  in  every  masonry  dam, 
some  provision  should  be  made  to  prevent  or  counteract  upward 
pressure  of  water  in  the  foundation.  The  amount  of  this  force 
cannot  possibly  be  foreseen  with  accuracy,  and  under  ordinary 
circumstances  cannot  be  foretold  within  rather  wide  limits. 

Any  foundation  for  a  masonry  dam  should  be  excavated  to 
a  plane  below  any  surface  disintegration.  Where  the  founda- 
tion is  seamy  and  pervious,  a  deep  trench  should  be  excavated 
along  the  heel  of  the  dam  to  be  later  filled  with  rich  concrete, 
thoroughly  rammed  and  bonded  with  the  masonry  of  the  dam. 

In  the  bottom  of  this  trench  holes  may  be  drilled  to  a  depth 
of  50  feet  or  more  below  the  bottom  of  the  trench,  and  by  forcing 
into  these  holes  cement  grout  under  high  pressure,  seams  and 
cavities  intercepted  may  be  filled  and  sealed  against  percolating 
waters.  The  drilled  holes  should  be  placed  at  intervals  of  5 
to  20  feet  or  more  according  to  the  conditions  of  greater  or  less 
permeability  found  to  exist.  The  attempt  is  to  form  an  imper- 
meable curtain  wall  to  a  great  depth,  to  prevent  water  from  pass- 
ing from  the  reservoir  under  the  dam. 

A  short  distance  downstream  from  this  cut-off  curtain 
another  series  of  holes  or  drainage  wells  should  be  provided 


EXPLORING  FOUNDATION  493 

to  intercept  whatever  water  may  find  its  way  into  the  founda- 
tion. These  should  be  about  6  inches  in  diameter,  and  8  to  10 
feet  apart,  along  the  entire  length  of  the  dam.  The  wells  should 
be  continued  upward  in  the  masonry  to  a  drainage  gallery 
just  above  the  natural  ground  surface,  which  will  discharge 
any  water  received  into  a  cross  conduit  leading  to  the  open 
river  below  the  dam. 

If  the  foundation  is  of  very  good  granite,  or  other  relatively 
impervious  rock  with  few  seams,  the  cut-off  and  grouting  pre- 
cautions need  not  be  as  elaborate  as  those  described,  but  the 
drainage  system  should  be  provided  in  any  case  of  a  high 
masonry  dam,  to  insure  against  uplift  in  the  foundation. 

13.  Exploring  Foundation. — Before  deciding  upon  the  suita- 
bility of  any  proposed  dam  site  it  is  necessary  to  ascertain  the 
character  of  the  foundation  and  the  depth  and  character  of  the 
bed  rock. 

Where  it  is  feasible  to  sink  open  shafts  and  test  pits  these 
are  the  most  satisfactory  means  as  they  afford  the  opportunity 
of  examining  the  material,  in  place,  but  they  are  expensive, 
and  where  water  is  to  be  encountered,  may  be  impracticable 
or  ineffective,  and  are  very  costly.  Where  the  material  passed 
through  is  to  be  used  as  the  foundation  of  dam  without  removal 
so  that  its  imperviousness  is  important,  the  material  itself  is 
not  more  important  than  the  manner  of  its  deposit,  and  test 
pits  are  the  only  satisfactory  means  of  examining  the  material 
in  place. 

Where  the  problem  is  the  depth  and  character  of  bed  rock, 
without  much  concern  as  to  the  character  of  the  overlying 
material,  the  most  economical  procedure  is  to  sink  an  iron 
casing  to  bed  rock  and  take  cores  from  the  rock  by  means  of 
the  diamond  drill.  The  process  of  sinking  of  the  casing  is 
performed  by  two  general  methods,  called  the  method  of  driv- 
ing and  the  method  of  wash  boring.  In  the  driving  method, 
the  casing  used  is  extra  heavy  steel  pipe  from  2  to  3  inches  in 
diameter,  cut  to  convenient  lengths,  which  are  fastened  together 
by  exterior  sleeves.  The  bottom  is  shod  by  a  short  cutting 
bit  of  tool  steel,  and  the  top  is  provided  with  a  solid  head. 


494  MASONRY  DAMS 

This  pipe  is  driven  like  a  pile,  and  the  interior  is  occasionally 
washed  out  with  a  chopping  bit  on  a  smaller  pipe,  provided 
with  a  water  jet.  When  bed  rock  is  reached  the  chopping  bit 
is  used  and  the  pipe  driven  until  some  penetration  of  the  rock 
is  secured  so  as  to  make  a  tight  connection  between  the  casing 
and  the  rock,  and  thus  exclude  sand  and  gravel.  The  diamond 
drill  is  then  applied  operating  inside  the  casing,  and  circular 
cores  of  the  rock  are  secured. 

By  the  "  wash-boring  "  method  flush- joint  pipe  is  used, 
which  is  not  so  strong,  but  sinks  more  readily  than  that  with 
sleeve  joints.  The  flush-joint  pipe  is  not  driven,  but  the  chop- 
ping bit  working  inside  is  freely  used  with  a  strong  water  jet. 
The  pipe  is  turned  round  and  round  by  means  of  tongs,  and 
sinks  of  its  own  weight  or  by  weights  resting  on  its  top,  following 
the  hole  made  by  the  chopping  bit  which  clears  the  way.  This 
method  is  usually  faster  and  cheaper  than  the  driving  method. 
When  the  diamond  drill  is  used,  it  may  pass  through  the  rock 
into  sand  and  thus  demonstrate  that  a  bowlder  and  not  bed  rock 
has  been  reached.  In  such  a  case  a  few  sticks  of  dynamite 
are  lowered  into  the  hole  drilled  in  the  bowlder,  and  after  with- 
drawing the  casing  a  few  feet  to  avoid  injury  the  cartridge  is 
exploded  electrically,  and  thus  the  bowlder  is  shattered  so  that 
the  casing  may  be  sunk  through  it  like  gravel. 

The  diamond  drill  should  be  made  to  penetrate  the  rock 
to  a  sufficient  depth  to  be  sure  that  it  is  bed  rock  and  not  a 
detached  bowlder  or  fragment  of  rock,  that  is  encountered,  and 
if  the  rock  is  not  of  satisfactory  character,  the  drilling  should 
continue  until  better  rock  is  reached,  or  the  prospect  of  satis- 
factory rock  disappears. 

Drilling  machinery  like  that  described  is  manufactured 
in  such  a  way  as  to  be  adapted  to  operation  by  hand,  and 
separable  into  parts  capable  of  transportation  by  laborers  or 
pack  animals.  Where  much  drilling  is  to  be  done  it  is  usually 
more  economical  to  use  heavier  machinery  with  steam  motive 
power. 

Such  a  machine  operated  by  hand  is  capable  of  drilling  200 
feet  into  solid  rock.  It  will  make  5  to  10  feet  per  day  in  hard 


EXPLORING  FOUNDATION  495 

rock  and  more  in  soft  rock.     By  the  use  of  steam  machinery 
much  faster  progress  can  be  made. 

REFERENCES  FOR  CHAPTERS  XVII  AND  XVIII 

CAIN,  WM.     Stresses  in  Masonry  Dams.     Trans.  Am.  Soc.  C.  E.,  vol.  LXIV,  p. 

208,  New  York. 
THOMPSON,  S.  E.     Impurities  in  Sand  for  Concrete.     Trans  Am.  Soc.  C.  E., 

vol.  65,  p.  250,  New  York. 
JORGENSEN,  L.  R.     The  Constant-angle  Arch  Dam.    Trans.  Am.  Soc.  C.  E., 

vol.  78,  p.  685,  New  York. 

CREAGER,  W.  P.     Masonry  Dams.     John  Wiley  &  Sons,  New  York. 
BLTGH,  W.  G.     Dams  and  Weirs.     American  Technical  Society,  Chicago. 
HARRISON,  C.  L.     Provision  for  Uplift  and  Ice  Pressure  in  Designing  Masonry 

Dams.     Trans.  Am.  Soc.  C.  E.,  vol.  75,  p.  142. 
RANDS,  HAROLD  A.     Grouted  Cut-off  for  the  Estacado  Dam.     Trans.  Am.  Soc. 

C.  E.,  vol.  78,  p.  447,  New  York. 
WEGMANN,  EDWARD.     Design  and  Construction  of  Dams.     John  Wiley  &  Sons, 

New  York. 
JORGENSEN,  L.  R.     Arch  Action  in  Arch  Dams.     Proceedings,  Am.  Soc.  C.  E., 

May,  1918. 
SCHEIDENHELM,  F.  W.     Reconstruction  of  Stony  River  Dam.     Trans.  Am.  Soc. 

C.  E.,  vol.  81,  p.  907. 
MEYER,  A.  F.     Elements  of  Hydrology.     John  Wiley  &  Sons,  New  York. 


CHAPTER  XIX 
WATER  RIGHTS 

1.  Nature. — The  title  to  water  is  no  less  important  than 
that  to  the  land  which  is  worthless  without  it.     Water  titles, 
however,  rest  upon  different  principles  from  those  to  land  and 
personal  property. 

2.  Riparian    Doctrine. — The    English    Common    law,    upon 
which  our  own  laws  are  based,  recognizes  the  riparian  doctrine, 
which  vests  in  the  owner  of  the  land  abutting  on  a  stream, 
the  right  to  have  the  stream  flow  past  his  land  in  perpetuity, 
undiminished  in  quantity  and  unimpaired  in  quality.     He  may 
use  the  water  for  domestic  and  milling  purposes,  but  must  return 
to  the  stream  before  it  leaves  his  property,  practically  the  same 
quantity  of  water  unpolluted;    otherwise  he  infringes  the  rights 
of  the  proprietor  of  the  land  below  him  on  the  stream. 

This  law  was  developed  in  England  in  a  humid  climate, 
and  provided  for  the  uses  of  water  then  and  there  common, 
but  is  not  adapted  to  the  development  of  irrigation,  being 
antagonistic  to  the  diversion  and  consumption  of  the  water 
in  the  growing  of  crops.  In  consequence,  the  needs  of  irriga- 
tion give  rise  to  a  radically  different  set  of  rules  for  the  control 
of  water.  All  irrigated  countries  recognize  the  right  to  divert 
and  consume  the  water  in  irrigation,  and  in  fact,  many  streams 
flowing  in  arid  regions  are  thus  diverted  and  almost  entirely 
consumed. 

3.  Doctrine    of   Appropriation. — In    the   United    States   the 
right  to   the  use  of  water  in  irrigation  originates  in  Federal 
Laws- recognizing  and  authorizing  such  use.-     Most  of  the  land 
of  the  arid   and  semi-arid  region  was    originally  public  land, 
and  under  the  riparian  doctrine  the  ownership  of  streams  was 

496 


DOCTRINE  OF  APPROPRIATION  497 

an  accompaniment  of  the  ownership  of  the  land.  The  necessity 
of  diverting  these  streams  to  irrigate  the  land  was  early  recog- 
nized and  was  provided  for  specifically  by  the  passage  in  1877 
of  the  Desert  Land  Act,  which  required  the  irrigation  of  the 
land  as  a  condition  of  ownership.  This  law  was  a  dedication 
of  the  water  by  its  owner  to  the  uses  of  irrigation,  and  thus 
made  all  unappropriated  waters  of  the  arid  region  perpetually 
subject  to  appropriation  for  irrigation,  except  when  expressly 
forbidden  as  in  the  case  of  navigable  streams.  Exceptions  to 
this  rule  are  the  cases  of  streams  running  through  large  Mexican 
land  grants  which  never  belonged  to  the  United  States,  and  the 
public  lands  of  Texas,  which  belonged  to  the  State  under  the 
provisions  of  the  act  admitting  that  State  to  the  Union. 

Notwithstanding  the  Desert  Land  Act,  and  the  need  of 
irrigation,  a  number  of  the  Public  Land  States  have  attempted 
to  apply  the  riparian  doctrine  to  the  waters  within  their 
boundaries.  This  is  particularly  evident  in  those  States  which 
are  partly  arid  and  partly  humid. 

The  first  American  attempt  to  assert  State  control  over  the 
use  of  water  in  irrigation  was  a  statute  passed  by  the  State  of 
Colorado  in  1879.  This  law  was  a  crude  one,  making  diversion 
the  test  of  appropriation,  and  ignoring  beneficial  use. 

Adjudications  under  this  law  were  made  by  courts  of  law, 
distant  from  the  lands  affected,  and  many  absurd  and  extrav- 
agant claims  were  allowed.  Many  cases  might  be  cited  where 
allowances  were  made  of  over  twenty  times  the  quantity  of 
water  that  could  be  beneficially  used,  and  far  in  excess  of  the 
capacity  of  the  ditches.  The  aggregate  of  allowances  were 
many  times  as  great  as  the  flow  of  the  stream  in  the  irrigation 
season. 

The  incompatibility  of  the  riparian  doctrine  with  the  needs 
of  irrigation  was  recognized  in  the  early  development  of  irriga- 
tion, and  the  eight  States  which  are  entirely  arid  or  semi-arid 
have  all  abrogated  this  doctrine,  and  have  substituted  the 
reverse  doctrine  of  appropriation  of  waters.  These  arid  States 
are  Arizona,  Colorado,  Idaho,  Montana,  Nevada,  New  Mexico, 
Utah  and  Wyoming.  There  are  eight  other  States,  however, 


498  WATER  RIGHTS 

which  are  partly  arid  and  partly  humid,  where  the  riparian 
doctrine  still  prevails  in  the  humid  portion.  Most  of  these 
States  have  the  bulk  of  their  population  in  the  humid  portion, 
where  riparian  rights  are  consistent  with  normal  development, 
and  where  the  inhabitants  are  unwilling  to  reverse  their  rules 
of  property  tenure  and  thus  interfere  with  vested  rights  for  the 
accommodation  of  a  small  minority  or  to  encourage  the  develop- 
ment of  a  distant  part  of  the  State.  In  these  cases  the  humid 
portion  of  the  State  was  first  settled,  and  as  the  needs  of  irriga- 
tion developed  various  attempts  were  made  to  reconcile  the 
antagonistic  riparian  and  appropriation  theories. 

In  two  States,  Washington  and  Kansas,  the  problem  was 
attacked  logically,  by  statutory  action  applying  different  rules 
to  the  arid  and  humid  regions.  In  Washington  the  principle 
of  appropriation  was  applied  to  Yakima  County  alone,  where 
the  main  irrigation  interests  lay,  and  in  Kansas  it  was  applied 
only  to  the  region  west  of  the  ggth  meridian,  which  is  the  arid 
portion  of  the  State. 

In  California,  Oregon,  Texas,  Nebraska,  and  South  Dakota 
efforts  were  made  to  apply  both  doctrines  and  the  result  was  a 
large  volume  of  diverse  and  inconsistent  court  decisions,  but 
mainly  having  a  tendency  to  modify  the  riparian  theory  as 
derived  from  the  common  law  in  order  to  adapt  it  to  the  needs 
of  irrigation.  As  an  early  step  in  this  process,  the  right  of 
appropriation  was  recognized  in  the  owner  of  riparian  lands, 
and  he  could  apply  the  water  to  such  area  as  he  saw  fit.  Some 
decisions  held  that  unless  this  right  was  exercised,  it  was  liable 
to  lapse,  and  another  could  appropriate  and  apply  the  water 
to  beneficial  use.  Whatever  the  theory  on  which  rights  to 
the  use  of  water  in  irrigation  are  founded,  all  of  them  recognize 
beneficial  use  as  the  indispensable  condition  of  a  permanent 
right;  but  this  is  a  long  and  expensive  process  in  most  cases, 
and  statutory  protection  is  very  desirable  to  protect  invest- 
ments until  it  can  be  perfected. 

In  the  absence  of  statutory  provisions,  it  is  often  the  custom 
to  initiate  a  water  right  by  filing  a  notice  at  or  near  the  point 
of  diversion,  and  record  this  action  in  some  county  record. 


DOCTRINE  OF  APPROPRIATION  499 

Such  claims  are  often  made  to  quantities  of  water  far  in  excess 
of  the  total  normal  flow  of  the  stream,  and  should  be  controlled 
by  engineering  authority  on  behalf  of  the  State. 

Until  recent  years  the  title  to  irrigation  water  was  in  a  very 
chaotic  state,  not  only  by  reason  of  conflicting  theories,  but 
for  the  lack  of  definite  statutory  direction  regarding  the  procedure 
to  acquire  and  perfect  a  title  to  the  use  of  water.  In  too  many 
cases  this  has  been  left  to  the  varying  judgment  of  the  courts 
and  diversion  and  inconsistent  rules  and  practices  have  been 
established. 

More  recently,  however,  many  of  the  States  have  adopted 
codes  recognizing  the  right  of  appropriation,  and  have  defined 
the  legal  steps  necessary  to  thus  initiate  a  right,  which,  however, 
remains  inchoate  until  perfected  by  the  application  of  the  water 
to  beneficial  use. 

The  insistence  of  all  irrigation  laws  upon  the  application  of 
water  to  beneficial  use  as  a  condition  of  title,  constitutes  a 
radical  difference  between  water  title  and  titles  to  land  which 
may  be  perpetual  and  incontestable,  without  any  pretense  of 
using  the  land  at  all.  Not  only  is  beneficial  use  required,  but 
the  tendency  is  to  make  this  requirement  more  and  more 
stringent.  A  well  established  title  to  water  may  in  most  States 
be  forfeited  by  abandonment,  or  by  non-use  for  a  specified 
time.  In  most  cases,  not  only  use,  but  a  reasonably  economical 
use  is  required.  Although  the  quantity  of  water  usually 
allowed  by  statute  or  by  court  decision  is  excessive,  the  prin- 
ciple is  maintained  that  there  can  be  no  title  to  water  to  be 
wasted. 

Some  of  the  constitutions  of  arid  States  assert  that  the 
waters  belong  to  the  public.  This  is  a  fundamental  denial 
of  riparian  rights,  but  is  always  followed  by  provision  for  the 
appropriation  of  water  to  private  use.  As  soon  as  this  is  accom- 
plished the  assertion  that  the  water  belongs  to  the  people  becomes 
a  fiction.  Attempts  are  made  to  disguise  this  fiction  by  contend- 
ing that  the  private  title  is  not  a  title  to  the  water,  but  only  a 
right  to  use.  But  as  this  right  to  use  is  perpetual,  and  in- 
volves the  right  to  consume  the  water  in  irrigation,  with  no 


500  WATER  RIGHTS 

obligation  to  return  it  to  the  public  nor  to  the  stream,  it  is  in 
reality  an  absolute  title,  limited  only  by  the  obligation  to  use  it 
beneficially. 

4.  Appurtenance  to  Land. — Aside  from  riparian  rights  there 
are  two  distinct  theories  of  the  ownership  of  water  rights. 
One  requires  the  appropriation  of  a  specific  quantity  of  water 
to  a  specified  tract  of  land.  When  it  is  desired  to  detach  a 
water  right  from  the  land  to  which  it  is  appurtenant,  it  is  neces- 
sary to  give  a  statutory  reason,  comply  with  certain  statutory 
formalities,  and  secure  official  permission,  at  the  same  time 
attaching  the  water  to  certain  other  lands,  so  that,  under  this 
theory  no  water  right  can  exist  except  as  appurtenant  to  certain 
land.  The  other  theory  permits  the  separate  ownership  of  land 
and  water,  and  thus  the  ownership  of  water  is  more  nearly 
analagous  to  that  of  land  than  under  the  requirement  of 
appurtenancy. 

Each  of  these  forms  of  water  right  has  its  advantages  and 
disadvantages.  A  separate  owner  of  water  may  own  no  land 
whatever,  and  may  lease  the  use  of  water  to  one  land  owner 
one  year,  and  to  another  the  next,  so  that  conceivably  some 
land  may  be  left  without  water,  and  perennial  crops  may  die, 
and  the  land  may  pass  out  of  cultivation  to  the  ruin  of  its  owner. 
It  is  argued  that  this  discourages  permanent  improvement; 
and  while  this  is  theoretically  true,  such  results  do  not  often 
follow  in  practice,  as  the  delivery  of  water  is  limited  by  the 
location  and  capacity  of  the  canal  system,  which  cannot  be 
conveniently  changed.  Permanent  improvements  and  perennial 
crops  such  as  fruit  trees  and  alfalfa  are  abundant  in  Utah 
where  separate  ownership  obtains.  The  possibility  of  the  owner 
of  water  to  deny  its  use  on  the  land  where  it  has  been  used,  or 
by  taking  advantage  of  the  farmer's  needs  to  demand  an 
exorbitant  price,  is  to  be  avoided,  and  it  is  generally  recognized 
that  the  doctrine  of  appurtenancy  is  the  better  public  policy. 

On  the  other  hand,  when  a  given  quantity  of  water  is  attached 
permanently  to  a  certain  tract  of  land,  it  often  occurs  that 
after  some  years  the  land  does  not  require  as  much  water  as 
has  been  attached  to  it,  and  the  tendency  is  to  continue  the 


APPURTENANCE  TO  LAND  501 

excessive  use  of  water  to  a  'disastrous  extent;  whereasj  if  the 
water  right  is  owned  separate  from  the  land,  although  both 
titles  may  be  and  usually  are  in  the  same  person,  the  owner 
has  the  incentive  of  self  interest  to  spread  it  over  all  the  land 
it  will  properly  serve,  to  secure  the  maximum  use,  and  thus  to 
promote  the  economy  of  water,  which  is  so  desirable  in  an  arid 
region. 

This  objection  to  appurtenant  water  rights  can  be  removed 
by  laws  and  customs  limiting  the  water  right  to  the  quantity 
actually  required  for  economical  use,  and  basing  operation 
and  maintenance  charges  on  quantity  used  so  as  to  put  the 
onus  of  economy  upon  the  user.  This  is  becoming  more  and 
more  the  practice,  and  with  this,  and  other  wise  provisions 
to  secure  economy  there  can  be  little  doubt  that  the  appurtenant 
water  right  is  to  be  preferred. 

• 
REFERENCES  FOR  CHAPTER  XIX 

MEAD,  ELWOOD.     Irrigation  Institutions.     Macmillan  Company,  New  York. 
CHANDLER,  A.  E.     Elements  of  Western  Water  Law.     Technical  Publishing  Co., 

San  Francisco,  Cal. 
JOHNSTON,  C.  T.     Some  Principles  Relating  to  Administration  of  Streams.     Trans. 

Am.  Soc.  C.  E.,  vol.  78,  p.  630,  New  York. 
LEWIS,  JOHN  H.     State  and  National  WTater  Laws.     Trans.  Am.  Soc.  C.  E.,  vol. 

76,  p.  637.     New  York. 


CHAPTER  XX 
OPERATION  AND   MAINTENANCE 

THE  operation  and  maintenance  of  a  system  of  irrigation 
canals  and  laterals  is  a  highly  specialized  activity,  involving 
different  branches  of  skill  for  different  systems.  All  of  them, 
however,  involve  human  as  well  as  physical  problems.  Some 
of  the  most  successful  operators  have  become  so  by  experience 
on  some  large  systems,  without  special  training  in  any  other 
branch  of  engineering,  but  there  are  advantages  in  a  general 
technical  training  which  appear  wherever  new  problems  arise. 

i.  Personnel. — Every  irrigation  system  of  considerable 
size  must  have  both  office  and  field  forces,  under  the  general 
charge  of  a  single  responsible  head. 

a.  Manager. — The  Project  Manager  should  be  responsible 
for  the  safe  and  permanent  maintenance  of  the  system,  and 
also   for  its  efficient  and   economical   operation.     In  addition 
to  ability  in  many  various  lines,  he  must  be  well  equipped  with 
experience,   judgment,   industry   and   tact.     If   he   is   deficient 
in  any  of  these  qualities  he  will  not  be  successful.     He  should 
have  an  assistant  manager  of  his  own  selection  and  in  close 
touch  with  him,  who  can  act  in  his  place  during  his  absence, 
and  to  whom  he  can  delegate  many  of  the  details  of  manage- 
ment.    They    should    alternate    to    a    certain    extent    between 
office  work  and  field  supervision,   so   that  one  of  them  may 
usually  be  found  at  headquarters,   and  both  will  be  familiar 
with  the  business  of  the  project,  in  field  and  office. 

b.  Canal    Superintendent. — A    large    project    is    generally 
divided  into  districts  each  of  which  is  in  charge  of  a  superin- 
tendent directly  responsible  to   the  Project  Manager  for  the 
efficient  delivery  of  water  and  the  execution  of  maintenance 

502 


PERSONNEL  503 

work.  He  is  provided  with  equipment  for  rapid  travel;  and  is 
assisted  by  such  canal  riders  and  gate  tenders  as  may  be  neces- 
sary. The  Superintendent  should  be  provided  with  a  telephone 
in  his  sleeping  quarters,  and  be  subject  to  call  at  all  hours  in 
case  of  a  break  in  the  canal,  or  other  emergency  requiring  his 
attention. 

c.  Canal  Riders. — Each  canal  rider  should  be  assigned  a 
definite  portion  of  the  canal  and  laterals  for  patrol,  and  for 
delivery  of  water  therefrom  to  water  users.     He  reports  to  the 
superintendent  every  day  by  letter  the  water  deliveries,  and 
promptly  by  telephone  any  urgent  matters  of  business  con- 
cerning the  condition  of  the  works  and  the  needs  of  the  water 
users  of  his  district.     The  canal  rider  must  be  an  intelligent  man, 
should  have  some  agricultural  training,  and  be  able  to  keep  neat, 
accurate   records.     He   must   be    energetic    and    vigilant    and 
possess    sufficient    tact    to    enforce    rigid    regulations    without 
unnecessary  friction.     He  must  be  able  and  willing  to  perform 
arduous  physical  labor  in  case  of  a  break  or  threatened  break 
in  the  canal.     Some  construction  experience  is  very  valuable 
to  him.     The  canal  riders  should  usually  be  employed  the  year 
round,  being  engaged  in  cleaning  and  repair  work  and  bringing 
the  records  into   shape  during  the  non-irrigation  season.     It 
is  good  practice  to  select  these  men  from  among  the  water  users, 
but  they  should  give  their  time  to  the  duties  of  canal  rider. 
Canal  riders  must  be  able  to  make  accurate  measurements  of 
small  streams,  and  to  use  intelligently  all  apparatus  employed 
for  this  purpose. 

The  canal  rider  should  patrol  his  beat  on  horseback  or  with 
a  small  cart.  A  bicycle,  automobile  or  motor  cycle  tends 
too  much  to  distract  his  attention  from  the  condition  of  the 
canal  and  its  structures,  which  it  is  his  peculiar  duty  to  inspect. 
He  should  usually  be  provided  with  two  horses  to  alternate 
on  duty. 

d.  Hydrographers. — On  large  systems  it  may  be  advisable 
to  have  an  assistant  engineer  skilled  in  all  kinds  of  stream 
measurement,  and  in  the  installation  and  repair  of  apparatus 
for  this  purpose,  to  keep  records  of  stream  flow  at  points  not 


504  OPERATION  AND  MAINTENANCE 

immediately  connected  with  any  canal  rider's  beat,  to  inspect 
such  observations  throughout  the  project,  and  to  digest  the 
results.  Particular  attention  should  be  given  to  the  measure- 
ment of  canals  and  laterals  at  points  where  the  results  will 
show  seepage  losses,  and  furnish  data  on  which  to  plan  improve- 
ments and  repairs. 

e.  Cooperation  with  Water  Users. — One  of  the  most  important 
duties  of  all,  from  Project  Manager  to  Canal  Rider,  is  to  keep 
in  sympathetic  touch  and  cooperation  with  the  water  users. 
The  first  duty  of  the  project  management  is  to  give  good  water 
service,  and  by  vigilance  and  activity  prevent  or  promptly 
repair  breaks,  and  thus  obviate  interruptions.  This  will  go  far 
to  secure  public  confidence,  but  is  not  alone  sufficient.  A 
patient  hearing  should  be  given  all  complaints,  and  careful 
investigations  should  be  made  with  a  view  to  the  removal  of 
all  just  grievances,  however  small.  Suggestions  for  improvements 
will  often  be  made,  and  these  should  be  carefully  considered, 
and  if  not  practicable,  the  reasons  for  not  adopting  them  should 
be  clearly  explained.  The  project  personnel  should  show  public 
spirit  and  concern  for  the  common  welfare,  even  along  lines 
not  strictly  connected  with  the  project  management.  In  every 
community  may  be  found  broad-minded  and  experienced  men 
whose  cooperation  along  progressive  lines  it  is  possible  to  obtain, 
such  as  improved  methods  of  irrigation,  drainage,  proper  selec- 
tion and  rotation  of  crops,  road  improvement,  cooperative 
marketing  and  other  measures  for  the  common  good. 

By  such  a  policy  it  is  possible  gradually  to  secure  the  con- 
fidence and  cooperation  of  the  water  users,  and  it  is  possible 
to  accomplish  far  more  by  cooperation  than  by  antagonism. 

2.  Economy  of  Water. — The  first  duty  of  a  project  manager 
is  to  insure  the  protection  and  maintenance  of  the  irrigation 
works.  The  second  duty  is  to  so  operate  them  as  to  give  reliable 
and  efficient  service  to  those  entitled  to  their  use.  The  third 
and  most  difficult,  and  consequently  most  often  neglected  duty 
he  has  to  perform  is  to  see  that  the  water  is  economically  used 
and  not  wasted. 

The  average  water  user  knowing  that  water  is  a  valuable 


ECONOMY  OF  WATER  505 

commodity  is  apt  to  regard  it  in  the  same  light  as  he  would 
regard  money  or  any  valuable  commodity,  and  he  feels  the  more 
he  can  get  the  better  he  is  off,  while  in  fact,  however,  from 
a  strictly  selfish  standpoint,  the  reverse  is  more  nearly  true. 

The  excess  application  of  water  is  often  positively  harmful 
to  the  crops  that  receive  it,  which  would  produce  better  with 
less  water.  If  the  surplus  drains  away  it  carries  with  it  plant 
food  in  solution  and  impoverishes  the  soil.  If  it  does  not  drain 
away  but  remains  in  the  water  table  it  soon  raises  this  water 
table  until  it  curtails  the  root  zone  in  which  plants  can  feed 
and  limits  production  in  this  way.  If  it  continues  to  rise  it 
eventually  kills  all  useful  vegetation,  and  this  condition  con- 
tinued forces  to  the  surface  whatever  alkaline  salts  are  contained 
in  the  soil  and  destroys  its  fertility. 

In  addition  to  all  the  above  reasons  it  is  to  the  interest  of  the 
country  at  large  and  in  a  broad  sense  to  each  irrigator  to  make 
the  best  possible  use  of  the  water  supply,  which  in  most  parts 
of  the  arid  region  is  the  limit  upon  agricultural  development. 
The  area  of  land  available  for  irrigation,  and  nearly  worthless 
without  it,  is  far  in  excess  of  the  water  supply  available  there- 
for, except  in  a  few  restricted  districts. 

The  measures  for  securing  the  best  use  from  the  available 
water  supply  depend  mainly  upon  the  farmer  himself,  but  such 
measures  can  be  encouraged  and  promoted  by  the  management 
not  only  by  agitation  and  other  educational  methods  but  by 
methods  of  water  delivery  and  the  adjustment  of  rates  of 
payment  therefor. 

The  encouragement  of  water  conservation  is  hampered 
by  the  necessity  which  exists  of  using  more  water  upon  new 
land  than  upon  land  which  by  cultivation  and  the  incorporation 
of  humus  therein  has  been  reduced  to  a  high  state  of  tilth. 
This  is  due  to  the  extreme  dryness  of  new  soil  in  the  arid  region, 
the  absence  of  humus  and  the  lack  of  that  homogeneity  or  mel- 
lowness which  follows  from  cultivation  and  mingling  of  organic 
matter  in  the  soil.  The  presence  of  organic  matter  or  humus 
renders  the  soil  more  retentive  of  water  and  less  subject  both  to 
evaporation  and  to  loss  of  water  into  the  water  table. 


506  OPERATION  AND  MAINTENANCE 

Another  reason  even  more  important  is  the  inexperience  of 
the  average  irrigator.  During  the  period  of  settlement  when 
only  a  fraction  of  the  land  is  in  cultivation  there  is  usually  a 
large  surplus  of  water  available  and  this  fact,  together  with 
the  reasons  above  mentioned,  make  the  practice  universal  of 
using  more  water  on  new  lands  than  they  really  need,  and  a 
great  deal  more  than  they  need  at  a  later  date. 

As  cultivation  proceeds  all  these  conditions  are  changed. 
The  farmer  to  succeed  must  put  humus  into  the  mineral  soils 
characteristic  of  the  arid  region  and  must  by  irrigation  and 
cultivation  break  up  the  stratification  and  induration  of  the 
various  constituents  of  the  soil,  making  it  more  homogeneous 
and  mellow.  The  irrigator  acquires  experience  with  time, 
and  the  wider  use  of  water  reduces  the  redundant  water  supply 
to  an  amount  just  sufficient  for  economical  irrigation  with  all 
the  land  in  cultivation.  But  in  the  meantime  habits  have 
been  formed.  Each  farmer  who  has  not  achieved  maximum 
results  is  apt  to  attribute  at  least  a  part  of  his  failure  to  a  fancied 
insufficient  supply  of  water  at  some  time  in  the  season,  whereas 
in  reality  such  shortage  as  he  may  have  suffered  has  been  due 
not  to  lack  of  water  but  to  inadequate  cultivation. 

It  has  been  previously  shown  that  soil  kept  in  a  thorough 
state  of  cultivation  with  the  surface  thoroughly  pulverized  at 
frequent  intervals  loses  water  much  less  rapidly  than  unculti- 
vated ground.  At  the  same  time  the  lack  of  cultivation  permits 
the  growth  of  noxious  weeds  which  extract  large  amounts 
of  water  from  the  soil  and  thus  in  two  ways  the  water  supply 
is  exhausted  and  the  crops  actually  suffer  from  drouth  even 
though  the  amount  of  water  applied  has  been  sufficient  for 
their  economical  use  under  proper  conditions.  Thus  the  farmers 
are  apt  to  resist  any  attempt  to  cut  down  the  supply  of  water 
as  furnished  during  the  early  stages  of  development  and  the 
opinion  of  the  manager  or  any  other  expert  who  advises  greater 
economy  is  apt  to  be  denounced  as  the  vaporings  of  swivel- 
chair  theorists,  as  against  the  experience  of  the  practical  farmer. 
The  result  is  generally  a  continued  over- application  of  water 
with  attendant  rise  of  ground  water  and  acute  seepage  con- 


ECONOMY  OF  WATER  507 

ditions,  calling  for  expensive  drainage  works  in  some  regions, 
and  a  serious  loss  of  plant  food  from  the  soils  of  other  regions. 
One  of  the  distressing  results  is  that  the  farmer  who  uses  water 
most  lavishly  may  not  perceptibly  injure  his  land  except  from 
loss  of  plant  food,  which  no  one  realizes,  but  the  excess  water 
he  applies  seeps  to  lower  levels  and  waterlogs  the  lands  of  his 
neighbors  who  may  be  using  water  with  a  fair  degree  of  economy. 
It  thus  often  happens  that  it  is  difficult  or  impossible  to  induce 
those  chiefly  responsible  for  seepage  conditions  to  join  in  the 
movement  to  correct  them  or  tc  provide  drainage  works  neces- 
sary for  the  salvation  of  the  lower  lands. 

This  creates  a  condition  where  the  management  is  blamed 
on  the  one  hand  for  shortage  of  water  due  to  alleged  inadequacy 
of  the  works  to  provide  the  lavish  quantity  used  in  the  early 
days,  and  criticism  of  the  builders  of  the  project  for  the  water- 
logged condition  and  a  demand  that  they  provide  drainage 
works. 

The  Project  Manager  must  keep  careful  records  of  the  water 
delivered  and  the  acreage  cultivated  from  the  inception  of  the 
project,  and  also  of  the  position  and  fluctuations  of  the  water 
table,  especially  as  this  approaches  the  root  zone  of  perennial 
plants.  It  is  only  by  having  complete  records  of  this  kind 
that  the  management  can  be  equipped  for  the  inevitable  cam- 
paign of  education,  and  the  possible  coercion  that  may  be 
necessary  to  prevent  the  destruction  of  values  in  an  irrigated 
valley. 

As  soon  as  feasible  the  practice  should  be  established  by 
charging  for  water  in  proportion  to  the  amount  used.  This 
practice  is  not  so  easily  inaugurated  as  may  appear  on  its  face. 

In  the  first  place  it  requires  careful  measurement  of  water 
thus  irrigated,  which  involves  considerable  investment  in  meas- 
uring devices,  and  considerable  skill  and  labor  on  the  part  of 
the  operating  force.  The  cost  of  this  may  be  criticized  by  the 
water  users  to  whom  it  is  charged,  and  their  resistance  has 
prevented  proper  administration  in  many  cases. 

The  full  application  of  the  principle  without  modification 
places  a  premium  upon  the  non-use  of  water  and  consequently 


508  OPERATION  AND  MAINTENANCE 

upon  the  non-cultivation  of  the  land  which  is  the  reverse 
of  what  is  desired.  On  the  other  hand  a  project  just  being 
opened  and  having  sandy  soil  with  a  porous  subsoil  may  be 
difficult  to  irrigate  without  applying  an  excess  quantity  of 
water  at  very  frequent  intervals  while  other  lands  perhaps 
even  more  productive  owing  to  different  soil  conditions  may 
be  served  with  a  fraction  of  the  quantity  of  water  necessary 
on  the  sandy  lands.  If  a  uniform  charge  for  water  by  quantity 
is  established  it  may  happen  that  in  order  to  collect  a  sufficient 
sum  for  the  operation  and  maintenance  of  the  project,  the  price 
must  be  fixed  so  high  as  to  be  oppressive  or  prohibitive  upon 
the  owners  of  the  sandy  lands  and  thus  more  harm  than  good 
might  proceed  from  such  a  rule.  For  these  reasons  much  care 
and  judgment  must  be  exercised  in  fixing  the  rates  to  encourage 
economy  of  water  and  penalize  its  waste,  without  restricting 
cultivation  or  oppressing  those  who  are  unfortunately  situated 
regarding  topographic  and  soil  conditions.  It  is  obvious, 
therefore,  that  every  individual  project  presents  a  problem 
or  series  of  problems  all  its  own  which  must  be  met  and  solved 
upon  their  merits. 

The  correctness  of  the  principles  here  advocated  are  recog- 
nized and  provided  for  in  the  United  States  laws  applying  to 
the  United  States  reclamation  projects.  Section  5  of  the  Act 
approved  August  13,  1914,  provides  as  follows: 

"  That  in  addition  to  the  construction  charge,  every 
water-right  applicant,  entryman,  or  landowner  under  or 
upon  a  reclamation  project  shall  also  pay,  whenever  water 
service  is  available  for  the  irrigation  of  his  land,  an  opera- 
tion and  maintenance  charge  based  upon  the  total  cost  of 
operation  and  maintenance  of  the  project,  or  each  separate 
unit  thereof,  and  such  charge  shall  be  made  for  each  acre- 
foot  of  water  delivered;  but  each  acre  of  irrigable  land, 
whether  irrigated  or  not,  shall  be  charged  with  a  minimum 
operation  and  maintenance  charge  based  upon  the  charge 
for  delivery  of  not  less  than  one  acre-foot  of  water." 
This  while  establishing  a  principle,  leaves  wide  discretion 
in  the  executive  officers  in  applying  the  principle.  To  start  with, 


ECONOMY  OF  WATER  509 

physical  conditions  make  it  necessary  to  collect  a  different 
total  amount  and  different  amount  per  acre  upon  each  system 
in  order  to  pay  the  cost  cf  operation  and  upkeep.  Different 
systems  and  different  parts  of  the  same  system  require  different 
quantities  of  water  for  proper  irrigation  due  to  soil  and  climatic 
and  other  conditions,  and  this  necessitates  a  different  rate  in 
order  to  raise  a  given  amount  of  money. 

Another  important  consideration  not  yet  mentioned  is  the 
necessity  of  bringing  some  pressure  to  bear  upon  the  irrigators 
to  accommodate  each  other  and  meet  the  demands  of  the  system 
concerning  the  time  of  application  of  the  water.  Where  the 
charge  is  made  by  quantity  there  is  a  general  tendency  to  post- 
pone irrigation  in  the  hope  of  rainfall  or  cool  weather  by  which 
a  little  water  would  be  saved,  then  a  hot  spell  may  cause  wilting 
of  the  crops  and  everybody  rushes  at  once  to  the  management 
for  immediate  delivery  of  water.  As  no  system  can  be  econom- 
ically constructed  adequate  to  irrigate  all  the  land  at  once,  it 
becomes  impossible  to  fulfill  all  these  requests  on  demand,  and 
inevitably  some  crops  must  go  short  of  water  during  the  criti- 
cal time,  and  heavy  losses  may  ensue.  To  avoid  this  the  carry- 
ing system  is  overtaxed  and  the  overloaded  canals,  attended  by 
an  overworked  operating  force,  are  apt  to  give  way  at  the 
critical  time  and  cause  widespread  destruction  both  to  the  lands 
devastated  by  the  broken  canals  and  to  those  that  need  the 
water  thus  suddenly  shut  off. 

It  thus  becomes  necessary  to  make  rules  by  which  a  farmer 
must  give  several  days'  notice  of  his  needs  so  that  these  needs 
can  be  adjusted  to  the  carrying  capacity  available,  and  the 
tendency  to  concentrate  the  requests  all  at  the  same  time  must 
in  some  cases  be  counteracted  by  an  adjustment  of  charges. 
It  is  therefore  advisable  in  many  cases  to  charge  more  for 
water  during  the  peak  of  the  season  than  at  other  times  in  order 
to  induce  earlier  use  of  water  and  prevent  overtaxing  the 
system  as  above  described. 

Experiments  have  shown  that  a  limited  quantity  of  water 
delivered  to  growing  plants  during  the  earlier  stages  of  growth 
yields  better  returns  than  the  same  quantity  of  water  applied 


510  OPERATION  AND  MAINTENANCE 

at  a  later  date.  Furthermore,  water  applied  early  in  the  season 
is  available  for  plant  use  throughout  the  season  so  long  as  it  is 
within  the  root  zone,  while  late  irrigation  often  leaves  the  root 
zone  charged  with  water  after  growth  has  ceased  and  the  water 
is  thus  wasted,  and  perhaps  contributes  to  raise  the  water  table. 

Still  another  reason  is  very  important.  Most  projects  are 
supplied  by  streams  which  yield  a  super-abundance  at  certain 
seasons,  and  decline  to  small  dimensions  at  other  seasons  and 
must  be  supplemented  by  expensive  storage  works.  To  get  the 
full  value  of  the  investment  in  storage  works  the  requirements 
of  economy  are  much  greater  during  the  season  when  stored 
water  must  be  used  than  during  the  season  of  abundance  when 
water  may  be  running  to  waste.  In  most  regions  the  spring 
and  early  summer  is  the  season  of  abundance,  and  streams 
decline  in  July  reaching  a  very  small  flow  in  August  and  Septem- 
ber. In  order  to  induce  early  irrigation  and  better  conserve 
the  storage  supply  it  may  be  advisable  to  adjust  the  charges 
so  as  to  encourage  early  use  of  water  and  penalize  excessive 
application  of  storage  water  later  in  the  season. 

The  law  above  quoted  has  been  found  adaptable  to  all  of 
these  varied  requirements  and  the  result  is  a  wide  variety  of 
terms  and  rates,  applied  to  the  different  projects  and  even 
different  parts  of  the  same  project.  In  order  to  avoid  penaliz- 
ing the  use  of  water  it  is  customary  to  make  a  flat  rate  which  shall 
apply  to  all  the  land  whether  water  is  used  or  not  and  which 
when  paid  will  entitle  the  landowner  to  a  quantity  of  water 
which  is  sufficient  for  economical  irrigation  under  the  most 
favorable  circumstances.  This  secures  the  collection  of  a  cer- 
tain amount  of  money  from  every  acre  and  thus  insures  the 
recovery  of  most  of  the  cost  of  operation  and  maintenance.  A 
moderate  charge  for  additional  water  will  make  it  to  the  interest 
of  every  man  to  use  water  with  economy.  This  charge  should 
be  moderate  until  the  limit  is  reached  beyond  which  any  applica- 
tion is  unquestionably  wasted;  thereafter,  the  charge  should 
increase  rapidly  and  finally  become  burdensome  so  as  to  prop- 
erly penalize  the  prodigal  waste  of  water. 

On   the   pumping   tract  of   the   Minidoka   Project,   Idaho, 


WANTON  WASTE  511 

where  it  is  necessary  to  prevent  a  sudden  demand  from  exceeding 
the  capacity  of  the  pumps  in  the  peak  of  the  season,  the  price 
of  water  is  fixed,  at  50  cents  per  acre-foot  for  deliveries  on  or 
before  June  5,  and  at  $1.00  per  acre-foot  after  that  date.  The 
high  price  is  continued  after  midsummer  on  account  of  the  use 
of  expensive  stored  water  in  the  late  summer  and  fall.  A 
minimum  charge,  however,  of  Si. 50  is  made  against  each 
irrigable  acre  whether  water  is  used  thereon  or  not,  and  this 
charge  is  credited  on  payments  for  water  under  the  acre-foot 
rates. 

From  long  investigations  and  study  of  results  in  Utah,  Dr. 
Widtsoe,  President  of  the  Utah  Agricultural  College,  concludes: 

"  The  Utah  results  would  lead  to  the  belief  that  where  the 
annual  rainfall  is  from  12  to  15  inches,  a  depth  of  water  from 
10  to  20  inches  is  best  for  ordinary  farm  crops,  and  that  the  best 
quantity  lies  nearer  the  smaller  figure.  A  depth  of  12  inches 
probably  represents  the  average  requirement  of  ordinary  farm 
crops,  providing  the  water  is  measured  at  the  intake  to  the 
farm." 

3.  Wanton  Waste. — First  of  all,  rules  must  be  rigidly  enforced 
forbidding  wanton  waste  of  water,  such  as  allowing  it  to  run 
at  night  without  benefit,  on  account  of  the  inconvenience  of 
night  work,  allowing  it  to  waste  in  large  quantities  from  the 
lower  end  of  the  field,  into  the  roads  or  waste  ditches,  and  other 
similar  practices. 

a.  Irrigation  at  Night. — In  the  early  development  of  some 
valleys,  while  irrigation  uses  are  small  and  the  water  supply 
abundant,  the  practice  grows  up  of  irrigating  during  daylight 
and  at  dusk  turning  the  water  into  some  draw  or  slough,  and 
allowing  it  to  run  to  waste  until  the  irrigator  is  ready  to  resume 
irrigation  the  following  day.  In  this  way  from  a  third  to  half 
of  the  water  is  wasted,  and  perhaps  contributes  to  raise  the  water 
table  and  aggravate  the  need  for  drainage,  which  is  almost 
certain  later  to  become  acute.  This  practice  may  be  hard  to 
break,  and  attempts  to  do  so  should  be  preceded  by  courteous 
explanations  of  the  necessity  for  the  reform.  It  is,  however, 
necessary  finally  to  do  this,  and  all  communities  where  good 


512  OPERATION  AND  MAINTENANCE 

results  are  obtained  with  a  reasonable  quantity  of  water,  give 
the  same  attention  to  the  control  of  water  at  night  that  they 
give  it  by  day. 

4.  Rotation. — In  some  regions,  especially  in  the  early  stages 
of  development,  it  is  the  practice  to  deliver  a  constant  flow  of 
the  average  quantity  to  which  the  irrigator  is  entitled,  and 
where  water  is  abundant  this  delivery  is  often  greatly  in  excess 
of  the  needs.  As  the  owner  of  a  small  farm  cannot  give  his  entire 
time  to  applying  irrigation  water  but  must  attend  to  other  duties, 
it  is  obviously  not  practicable  to  use  water  economically  in  this 
way.  Much  better  results  can  be  had,  higher  economy  attained 
and  much  time  saved  by  delivering  water  at  intervals  in  larger 
volumes.  This  practice  also  promotes  important  economies 
for  other  reasons  as  when  a  small  quantity  of  water  is  turned 
on  at  the  upper  end  of  the  field  it  is  absorbed  by  the  land  first 
reached  and  progresses  very  slowly  to  the  lower  end,  and  before 
a  sufficient  quantity  has  reached  the  lower  end  of  the  field  for 
proper  irrigation  a  great  deal  of  the  upper  end  of  the  field  has 
become  over-saturated  and  water  is  flowing  by  gravity  into  the 
subsoil,  finally  to  reach  the  water  table  and  be  wasted.  Much 
higher  economy  both  in  time  and  water  can  be  obtained  by  turn- 
ing on  a  large  quantity  at  once  so  as  to  cover  the  ground  several 
inches  in  depth  and  while  the  water  in  contact  with  the  soil 
is  being  absorbed  the  surface  water  is  run  rapidly  toward  the 
lower  end  of  the  field.  The  entire  surface  is  thus  soon  wet 
and  the  irrigation  of  a  given  district  is  soon  over  and  the  water 
is  carried  to  additional  fields.  If  a  farm  of  100  acres  is  entitled 
to  an  average  flow  of  i  cubic  foot  per  second,  it  is  best  to  commute 
it  into  a  flow  of  5  to  10  cubic  feet  per  second,  deliver  for  one-fifth 
or  one- tenth  of  the  time;  then  by  giving  careful  attention  to 
the  use  of  the  water,  irrigation  is  accomplished  better  and  the 
irrigator  has  a  major  portion  of  his  time  for  other  duties,  and 
while  engaged  upon  them  his  neighbors  are  using  water  in  a 
similar  manner.  Such  a  system  requires  turnouts,  laterals  and 
farm  ditches  constructed  with  rotation  methods  in  view  and 
these  should  be  provided  in  the  construction  of  an  irrigation 
system. 


ROTATION  513 

It  is  necessary  to  use  much  larger  heads  for  irrigation  on 
very  sandy  soils  where  percolation  is  rapid  than  upon  tight 
soils  which  require  a  great  deal  of  time  to  absorb  the  requisite 
amount  of  water.  It  is  also  practicable  to  use  much  larger 
heads  on  comparatively  level  ground  than  upon  steep  slopes, 
and  next  to  the  skill  of  the  irrigator,  the  grade  of  the  land  to 
be  irrigated  is  the  most  important  element  in  the  limit  of  head 
which  it  is  practicable  to  use. 

The  introduction  of  such  a  rotation  system  is  a  matter  of 
considerable  difficulty  and  it  will  be  difficult  to  overcome  the 
established  habits  and  prejudices. 

The  rotation  method  of  delivery  of  water  is  employed  on 
the  Okanogan  System  in  Washington,  the  system  being  to  allow 
a  water  user  for  one  week  double  the  amount  of  water  which 
would  be  required  for  constant  flow,  and  then  one  week  without 
any  water  delivery. 

This  schedule  is  worked  out  before  the  irrigation  season 
begins  and  each  water,  user  is  notified  of  the  dates  on  which 
he  will  receive  water.  The  schedule  is  adhered  to  as  nearly 
as  possible,  but  numerous  modifications  have  to  be  made  to 
accommodate  the  irrigators. 

The  system  as  worked  has  been  found  reasonably  economical 
of  water  and  of  labor,  and  is  satisfactory  to  the  water  users. 

The  lateral  system  on  the  Salt  River  Valley,  Arizona,  was 
so  designed  as  to  deliver  to  each  quarter  section  of  land  a  head 
of  10  second-feet  of  water.  For  many  years  the  custom  was 
followed  of  delivering  such  head  for  a  period  of  twenty-four 
hours  in  every  eight-day  period,  seven  days  without  water, 
and  for  smaller  farms,  a  proportionately  shorter  time,  with 
the  same  interval. 

In  1912  the  basis  of  charge  was  changed  from,  the  flat  rate 
to  payment  for  quantity  of  water  used  in  order  to  encourage 
economy,  and  the  rigid  rotation  system  was  varied,  water  being 
delivered  in  large  heads,  but  instead  of  a  regular  rotation, 
deliveries  are  made  in  accordance  with  requests  which  are 
required  to  be  presented  twenty-four  hours  or  more  in  advance 
of  the  need.  From  these  requests,  rotation  schedules  are  made 


514  OPERATION  AND  MAINTENANCE 

up  from  day  to  day  as  far  in  advance  as  possible,  and  in  most 
cases,  it  is  feasible  to  deliver  water  in  accordance  with  the 
requests  made. 

During  the  maximum  demand  for  water,  these  requests 
frequently  conflict  to  such  an  extent  as  to  make  their  compliance 
impossible,  and  notice  is  served  that  the  water  will  be  de- 
livered on  a  rotation  system. 

When  a  lateral  is  on  a  rotation  basis,  it  is  the  custom  to 
begin  at  the  lower  end  and  work  up  to  the  head  of  the  lateral, 
giving  to  every  water  user  a  head  from  yj  to  10  second-feet 
for  from  twenty-four  to  thirty-six  hours  for  each  quarter  section 
of  land.  Generally  when  the  demand  for  water  at  any  partic- 
ular time  has  been  greater  than  the  capacity  of  the  canal  to 
supply,  it  is  necessary  only  to  advise  the  farmers  that  the  canal 
will  be  placed  on  a  regular  rotation  basis  and  the  demand 
immediately  decreases,  the  farmer  being  willing  to  wait  a  few 
days  for  water  rather  than  have  the  canal  placed  on  regular 
rotation. 

The  delivery  head,  however,  is  the  same  for  both  plans  of 
delivery,  and  the  method  followed  on  the  Salt  River  Project 
is  very  economical,  both  of  time  and  of  water.  Most  of  the 
irrigation  in  Salt  River  Valley  is  done  under  the  border  method 
described  on  page  112. 

Regardless  of  crops  raised,  the  border  system  is  the  best 
method  of  irrigating  porous  soils,  unless  the  ground  is  too  steep 
for  this  method.  On  very  rolling  land,  so  steep  that  the  flood- 
ing or  border  method  is  not  practicable  as  a  means  of  distribut- 
ing water  the  furrow  system  is  generally  used.  The  furrows 
may  be  run  on  any  grade  desired  between  the  steepest,  directly 
down  the  hill,  and  a  level  line  along  contours.  The  more  open 
the  soil  the  steeper  must  be  the  slope  of  the  furrows.  This 
may  range  from  about  2  per  cent  on  open  sandy  soil  where  the 
water  must  be  hurried  across  the  field,  to  about  one- tenth  of 
this  slope,  or  2  feet  per  thousand  for  loam  or  clay  soils  where 
more  time  for  absorption  must  be  given. 

5.  Basis  of  Charges. — It  is  becoming  more  and  more  the 
practice  to  fix  charges  for  operation  and  maintenance  in  accord- 


CULTIVATION  515 

ance  with  the  quantity  of  water  used,  and  to  encourage  economy 
by  this  means.  To  insure  the  collection  of  sufficient  revenue 
for  expenses,  and  also  to  compel  those  who  do  not  cultivate 
their  holdings  to  pay  a  proper  share  of  expenses,  it  is  best  to 
establish  a  flat  rate  of  charge  per  acre,  which  will  entitle  the 
irrigator  to  about  the  quantity  of  water  necessary  for  economical 
irrigation,  and  then  fix  a  reasonable  charge  for  all  additional 
water  used.  This  has  a  tendency  to  encourage  proper  use  of 
water  and  to  penalize  waste,  but  accomplishes  little,  unless 
accompanied  by  a  system  of  rotation  delivery,  and  careful 
night  irrigation.  The  variety  of  human  and  physical  con- 
ditions lead  to  widely  various  application  of  the  above  rules 
for  charges. 

The  projects  vary  widely  in  many  respects.  Some  are 
expensive  to  operate  in  proportion  to  the  acreage  served  and  some 
are  cheap.  Some  have  an  abundant  water  supply,  and  on 
others,  the  supply  must  be  stretched  to  the  utmost.  Some 
have  stored  water,  while  others  depend  on  natural  stream  flow. 
On  some  delivery  capacities  are  rigidly  limited  by  pumps, 
expensive  tunnels,  or  similar  works,  while  simpler  projects  are 
more  generously  endowed  in  this  respect.  Some  have  a  rea- 
sonably uniform  soil,  while  on  others  the  soil  ranges  from  heavy 
clay  to  coarse  sand  with  gravel  subsoil.  Some  have  a  growing 
season  of  4  or  5  months  while  others  range  from  6  to  12.  Some 
lands  require  but  a  small  quantity  of  water  for  good  results, 
while  others  require  several  times  as  much. 

These  varying  characteristics  occur  in  all  conceivable  com- 
binations, and  each  project  presents  a  distinct  problem  which 
must  be  considered  by  itself,  and  changes  from  year  to  year,  as 
development  progresses.  The  provisions  applying  the  above 
law  are  given  in  Table  XXIV,  page  145. 

6.  Cultivation. — Experiments  have  shown  that  a  vigorous 
growing  crop  transpires  more  water  to  the  atmosphere  than  is 
evaporated  from  the  surface  shaded  by  such  a  crop,  but  the 
evaporation  from  the  ground  still  remains  very  important 
unless  it  is  assiduously  cultivated.  After  each  irrigation  there 
is  a  tendency  for  the  surface  of  the  ground  to  bake  under  the 


516  OPERATION  AND  MAINTENANCE 

hot  sun,  except  on  very  sandy  soils.  When  this  occurs,  capil- 
lary attraction  is  very  strong,  and  the  water  is  rapidly  drawn 
to  the  surface  and  evaporated.  This  can  be  remedied  by 
thoroughly  stirring  the  surface  of  the  soil  breaking  the  crust 
and  providing  a  mulch  of  pulverized  loose  soil,  which  holds 
the  moisture  and  reduces  evaporation  to  one-half  or  one-third 
what  it  would  be  without  such  cultivation.  This  also  kills 
the  weeds  and  conserves  plant  food,  by  keeping  the  water  in 
the  ground  a  long  time  before  taken  up  by  the  plants  thus 
giving  it  time  to  dissolve  the  minerals  of  the  soil  which  serve 
as  food  for  the  plants.  Fresh  water  applied  to  a  field  can 
convey  but  little  nourishment  to  the  plants,  especially  of  the 
mineral  character,  and  for  this  reason  it  is  much  better  to 
conserve  water  in  the  soil  for  a  long  time  than  to  allow  it  to 
evaporate  rapidly  and  irrigate  with  fresh  water.  It  is  impor- 
tant, therefore,  to  cultivate  soon  after  irrigation  as  the  surface  is 
sufficiently  dry  for  the  purpose,  and  it  is  necessary  for  constant 
effort  to  be  put  forth  to  induce  the  farmers  to  do  so. 

7.  Winter  Operation  of  Irrigation  Canals. — In  semi-tropical 
regions  it  is  usually  necessary  to  operate  irrigation  canals  the 
year  round  and  it  then  becomes  at  times  difficult  to  secure 
enough  respite  to  afford  opportunity  for  necessary  cleaning  and 
repairs.  This  must  usually  be  obtained  in  short  periods  in  the 
winter  season  between  crops  or  immediately  after  rains. 

In  the  extreme  North  the  long  severe  winters  make  winter 
operation  not  only  practically  impossible  but  relatively  unde- 
sirable; in  middle  latitudes,  however,  where  six  months  of  the 
year  are  frosty  and  irrigation  is  not  required,  it  may  be  neces- 
sary, and  on  new  projects  usually  is  desirable,  to  have  water 
available  for  domestic  and  stock  use  and  the  demand  for  this 
use  is  sometimes  very  insistent.  Arguments  are  also  advanced 
that  winter  irrigation  is  beneficial  and  is  necessary  also  for 
sprouting  of  winter  grain  crops  and  the  moistening  of  land  for 
winter  plowing. 

The  operation  of  canals  through  months  of  freezing  weather 
is  open  to  many  objections: 

i.  It  delays  or  prevents  adequate  cleaning  and  maintenance 


WINTER  OPERATION  OF  IRRIGATION  CANALS  517 

work  and  therefore  cripples  the  efficiency  of  the  canals  for  their 
real  purpose  of  summer  irrigation. 

2.  Water    held    continuously    in   canals   results    in    serious 
deterioration  of  the  banks  which,  becoming  saturated,   freeze 
and  by  the  expansion  of  the  ice  leave  the  banks  more  or  less 
open    and    porous,    increasing    the    dangers    of    seepage     and 
sloughing. 

3.  It  increases  the  leakage  of  the  canals  by  extending  this 
through  the  winter  and  thus  results  in  increased  seepage  and 
rise  of  water  table,  tending  to  destroy  the  agriculture  of  lands 
under  the  canal  or  to  add  to  the  cost  of  drainage. 

4.  Irrigation  works  are  not  designed  with  a  view  to  operation 
under  frost  conditions,  and  the  effect  of  freezing  upon  concrete 
structures  often  causes  rapid  deterioration. 

5.  Irrigation  canals  do  not  ordinarily  furnish  water  supply 
suitable  for  domestic  purposes  and  their  unavoidable  contami- 
nation renders  the  water  unsanitary  and  dangerous. 

6.  Live  stock  is  much  better  off  in  winter  when  supplied 
with  clean  and  wholesome  well  water  at  underground  tempera- 
ture, which  conserves  animal  heat  and  health  and  saves  much 
feed. 

It  is  best,  therefore,  to  provide  supplies  of  well  water  for 
stock  and  domestic  purposes  as  soon  as  practicable.  Experience 
shows  that  after  the  first  year  or  two  most  of  the  settlers  provide 
themselves  with  domestic  water  supply  of  better  quality  than 
canal  water  if  this  is  at  all  feasible,  and  the  demand  for  winter 
operation  is  usually  by  a  small  minority  of  the  settlers.  But 
even  where  this  is  not  so  the  financial  and  sanitary  considera- 
tions involved  are  strongly  on  the  side  of  closing  the  canals 
as  early  as  possible  in  the  autumn,  thus  giving  plenty  of  open 
weather  for  cleaning  and  repairs  and  letting  the  banks  dry  out 
before  the  hard  freezing  weather  arrives.  The  canals  are  then 
in  shape  to  secure  satisfactory  results  when  opened  in  the  spring. 

This  policy  also  has  usually  a  beneficial  effect  on  the  ground 
water  conditions,  as  the  contribution  of  water  from  the  canals 
is  thus  shut  off.  In  some  localities,  where  the  water  table  is 
already  high  near  the  canals,  they  operate  as  drains  for  a  time 


518  OPERATION  AND  MAINTENANCE 

after  the  water  is  shut  out  in  the  fall,  and  thus  hasten  the 
lowering  of  ground  water  which  occurs  during  the  non-irrigation 
season. 

Where  winter  delivery  is  necessary  the  burden  of  operation 
cost  should  be  borne  by  those  who  demand  it,  and  deliveries 
made  only  to  those  who  share  the  expense.  This  problem 
is  met  on  one  of  the  Government  systems  by  the  following 
regulation : 

a.  Optional  Water  Service. — Until  further  notice,  after 
October  20  of  each  season  no  water  will  be  furnished  except 
upon  request,  and  at  an  additional  charge  for  each  farm-unit 
of  eighty  acres  or  fraction  thereof,  of  $2.00  for  each  day  of  water 
service  given.  Provided,  however,  that  every  person  desiring 
this  service  shall,  before  receiving  same,  deposit  with  the  Special 
Fiscal  Agent  of  the  United  States,  a  sum  of  money  sufficient  to 
cover  the  number  of  days  that  he  desires  water  and  designate  the 
turnout  where  he  wishes  to  have  the  water  delivered  and  the 
size  of  stream  he  will  require.  So  far  as  may  be  practicable, 
water  will  be  delivered  to  each  depositor  for  the  days  covered 
by  his  deposit,  but  whenever  the  aggregate  deposits  for  any 
day  are  less  than  $200,  delivery  of  water  will  cease  and  will  not 
thereafter  be  resumed.  Any  unused  deposits  will  be  returned 
to  the  persons  by  whom  they  were  made.  This  service  will 
not  be  commenced,  however,  unless  deposits  aggregating  $200 
per  day  for  a  reasonable  period  shall  be  made  prior  to  October  20. 

8.  Maintenance. — An  efficient  rotation  system  will  give 
occasional  opportunities  during  the  irrigable  season  for  necessary 
cleaning  and  repair  work  on  small  laterals,  and  the  opportunity 
to  perform  this  work  when  most  convenient  or  economical  is 
an  important  advantage  of  such  a  system.  This,  however,  can- 
not apply  to  the  main  canal,  nor  to  the  larger  laterals,  which 
must  be  used  throughout  the  summer.  In  Southern  Arizona 
and  California  the  demand  for  irrigation  water  throughout 
the  year  presents  a  difficult  problem  in  maintenance  and  repairs, 
and  great  care  and  energy  are  essential  to  perform  these  neces- 
sary duties  properly,  without  seriously  interfering  with  proper 
irrigation.  The  demand  for  water  is  much  less  in  winter  than 


EROSION  519 

in  summer,  and  a  brief  shortage  produces  less  disastrous  results. 
Such  work  as  can  be  done  with  water  running  in  the  canals, 
is  so  performed,  and  the  rest  is,  if  possible,  postponed  till  the 
fall  or  winter  months.  By  closing  one  large  lateral  at  a  time 
after  due  notice  to  the  irrigators,  concentrating  a  large  force 
there  and  pushing  the  work,  the  annual  maintenance  work  may 
usually  be  performed  on  these  with  little  inconvenience  to  any- 
one. The  main  canal  is  treated  in  the  same  way,  selecting 
for  this  the  period  of  least  demand  for  water,  usually  in  January. 

In  more  northern  latitudes  with  shorter  season,  the  water 
should  be  turned  out  of  the  canals  after  ample  notice  to  every- 
body, as  early  in  the  fall  as  conditions  will  permit,  and  a  strong 
force  previously  organized  should  immediately  be  set  to  work 
to  perform  the  annual  maintenance  work.  A  careful  inspection 
of  the  canal  and  all  structures  should  be  made,  and  their  con- 
dition recorded  for  present  and  future  use. 

9.  Erosion. — Where  erosion  of  one  bank  is  noted,  this  should 
be  attended  to.  If  it  is  due  to  some  obstruction  on  the  other 
side  of  the  canal  as  a  sand  bar  or  other  drift  this  should  be 
removed.  If  the  erosion  is  on  the  outside  of  a  curve  in  the 
canal  this  may  be  corrected  by  deepening  the  canal  on  the  inner 
side  of  the  curve,  to  induce  a  stronger  current  on  that  side, 
and  using  the  material  removed  to  flatten  the  slope  on  the 
opposite  side.  If  gravel  can  be  obtained  a  carpet  of  this  may 
be  placed  on  banks  showing  moderate  erosion.  In  case  of 
necessity  the  points  attacked  may  be  protected  by  riprap  of 
rock,  or  in  some  cases  sage  brush  had  better  be  employed. 

Rock  riprap  has  been  much  used,  but  is  always  costly  and  is 
not  efficient  unless  laid  in  a  very  expensive  manner.  Unless 
the  riprap  is  started  below  the  canal  bottom  and  the  joints  well 
plastered,  it  soon  fails  in  sandy  soil  by  the  washing  out  of  the 
sand  between  the  cracks.  Brush  of  any  kind,  weeds  and  grass 
will  do  temporarily,  but  the  latter  are  good  for  but  one  season. 
Sage-brush  is  especially  adapted  to  this  purpose,  being  bushy, 
flexible,  durable  and  tough. 

A  method  extensively  used  is  to  plow  a  deep  furrow  in  the 
bank  about  a  foot  below  where  the  damage  is  likely  to  occur 


520  OPERATION  AND  MAINTENANCE 

and  smooth  this  out  with  a  small  V-shaped  scraper  which  leaves 
a  terrace  about  i\  feet  wide.  On  this  a  layer  of  brush  is  placed 
with  butts  to  the  bank  and  tops  sloping  toward  the  water  and 
downstream  30  to  40  degrees,  the  tops  being  kept  in  careful 
alinement.  After  the  first  row  has  been  laid,  another  furrow 
is  plowed  higher  up  the  bank  and  smoothed  out  with  a  scraper, 
pushing  the  dirt  over  the  first  layer  and  effectively  binding  it 
without  the  use  of  stakes.  This  process  is  repeated  until  the 
riprap  is  a  foot  above  the  maximum  water  surface.  When 
finished,  the  tops  of  the  brush  should  extend  8  inches  beyond 
the  earth  they  are  buried  in,  but  must  not  encroach  upon  the 
original  canal  section. 

The  distance  vertically  between  layers  of  brush  and  the  den- 
sity of  each  layer  should  vary  with  the  velocity  of  the  water. 
For  velocities  below  3  feet  per  second,  the  density  of  the  riprap 
may  be  about  equal  to  that  of  the  branches  in  the  average  sage- 
brush, and  this  should  increase  with  higher  velocities. 

On  the  Minidoka  Project  a  large  amount  of  such  riprapping 
was  done  at  costs  varying  from  10  to  14  cents  per  square  yard. 

10.  Silt  Deposits. — Accumulations  of  sand  or  silt  should 
be  removed  and  their  cause  noted.  If  it  is  due  to  some  local 
obstruction  producing  an  eddy  or  other  removable  cause,  this 
should  be  corrected. 

Dead  weeds  drifting  into  the  canal  should  be  removed  and 
burned.  Weeds,  brush  and  grass  growing  in  or  very  near  the 
waterway  will  obstruct  the  flow  and  cause  deposits  of  silt,  and 
should  be  removed.  If  this  is  done  cleanly  annually  or  oftener 
it  will  be  less  expensive  than  if  postponed  until  the  nuisance 
becomes  acute. 

Where  excessive  seepage  has  occurred  it  may  be  advisable 
to  excavate  the  channel  larger  and  refill  with  clay  puddle. 
This  method  is  described  on  page  233.  Where  the  water  carried 
is  heavily  silt-laden,  extensive  deposits  of  silt  may  occur  through- 
out the  canal  system,  and  must  be  removed  by  mechanical 
means.  This  is  done  from  small  canals  in  the  southwestern 
valleys  where  this  problem  occurs,  by  means  of  a  V-shaped 
drag  or  plow  with  a  cutting  edge,  pulled  by  one  or  more  traction 


ALKALI  521 

engines.  It  is  necessary  for  the  V  to  travel  down  each  side, 
and  it  is  not  applicable  to  canals  of  more  than  10  feet  bottom 
width  nor  4  feet  depth.  Larger  canals  may  be  cleaned  of  silt 
by  dredges  traveling  on  the  banks,  or  floating  on  barges.  The 
drag  line  type  is  best  adapted  to  this  use. 

11.  Alkali. — In  some  regions  concrete  is  attacked  and  slowly 
disintegrated    by    alkali,    usually    sulphates.     The    damage    is 
generally  caused  by  alkaline  ground  water,  which  is  absorbed 
by  the  concrete,  whence  the  water  evaporates  leaving  the  salts 
to  crystallize  in  the  body  of  the  concrete,  and  disintegration 
follows,    apparently   as   a   mechanical   result.     The   structures 
usually  attacked  are  those  in  contact  with  the  ground  on  one 
side,  and  with  the  air  on  the  other,  such  as  culverts,  and  canal 
linings  while  not  covered  by  canal  water.     A  structure  standing 
in  alkaline  ground  may  absorb  ground  water,  which  by  capillary 
attraction  percolates  upward,  and  evaporates  from  the  surface 
above  ground,  and  disintegration  begins  just  above  the  ground, 
and  extends  as  high  as  the  ground  water  rises.     The  preventive 
most  often  attempted  is  to  make  the  concrete  as  dense  as  pos- 
sible by  careful  mixing  and  placing,  so  as  to  reduce  its  absorp- 
tion to  a  minimum.     It  may  be  that  a  coating  of  tar  or  other 
waterproof  material  can  be  placed  on  the  side  next  the  ground 
water,  and  this  may  prevent  attack.     Another  method,  applicable 
to  canal  lining  and  some  other  cases,  is  to  drain  the  ground  water 
from  the  vicinity  of  the  concrete  by  a  layer  of  screened  gravel, 
leading  to  some  escape. 

12.  Growth  of  Aquatic  Plants. — Where  clear  water    is  run 
in  earth  canals,   especially   at  a  low  velocity,   the  growth  of 
aquatic  plants  sometimes  reaches  a  profusion  that  gives  serious 
trouble.     There   are   several   species   of    these  plants   some   of 
which  have  long  stems,  and  by  friction  upon  the  flowing  water, 
impede  the  velocity  and  thus  cut  down  the  capacity  of  the  canal 
until  it  often  becomes  imperative  to  remove  the  vegetation  in 
order  to  restore  sufficient  capacity  for  the  needs  of  the  crops. 
Such  growths  seldom  become  troublesome  when  the  water  is 
continuously  turbid,  nor  under  bridges  where  the  shade  is  dense. 
They  are  more  troublesome  in  shallow  than  in  deep  canals, 


522  OPERATION  AND  MAINTENANCE 

and  do  not  thrive  generally,  in  water  more  than  4  or .  5  feet  in 
depth.  They  need  sunlight  and  heat,  and  seldom  bother  when 
temperatures  of  water  are  kept  below  65  degrees.  They  are 
especially  troublesome  in  canals  of  low  velocity,  although  when 
other  conditions  are  favorable,  they  occur  in  canals  with  velocity 
as  high  as  2j  feet  per  second. 

The  experience  of  the  U.  S.  Reclamation  Service  indicates 
that  the  velocity  should  be  at  least  2\  feet  per  second  to  insure 
against  troublesome  growth  of  aquatic  plants.  Etcheverry 
concludes  from  study  of  all  available  data  that  instances  of 
troublesome  growths  in  velocities  above  2  feet  per  second  are 
few  and  practically  none  for  velocities  greater  than  2  J  feet  per 
second. 

Numerous  methods  of  combating  these  pests  have  been 
tried  from  time  to  time,  with  various  degrees  of  success. 

Where  the  climate  is  especially  hot  and  dry  the  plants  are 
sometimes  killed  by  shutting  the  headgates  and  allowing  the 
water  to  drain  out  of  the  canals  and  laterals  affected,  which 
dries  the  plants  and  kills  them  in  from  two  to  five  days  under 
favorable  conditions.  This  will  not  work,  however,  where  the 
grade  of  the  canals  is  slight  as  the  water  is  then  held  by  the 
plants  as  a  sponge,  and  does  not  drain  sufficiently  to  kill  the 
plants  in  a  reasonable  time,  but  where  the  grade  and  velocity 
are  ample  and  the  humidity  low  it  has  been  known  to  succeed. 
It  seems  to  be  more  effective  with  some  species  than  with  others. 

Aquatic  plants  do  not  grow  to  a  harmful  extent  in  muddy 
water,  and  where  the  conditions  are  favorable  benefit  may  be 
derived  from  an  application  of  the  silting  process,  so  as  to  keep 
the  water  muddy  for  several  weeks.  To  be  effective,  this  remedy 
must  be  applied  before  the  plants  have  reached  any  considerable 
size  and  vigor,  and  should  be  continued  until  its  effect  is 
complete. 

Where  neither  of  these  means  can  be  successfully  used,  the 
plants  may  be  removed  by  mechanical  means.  Several  devices 
have  been  tried  for  this  purpose. 

A  small  chain  to  which  are  attached  lead  weights  has  been 
dragged  along  the  bottom  of  the  canal  by  a  team  on  each  bank 


GROWTH  OF  AQUATIC  PLANTS  523 

attached  to  the  ends  of  the  chain.  Little  success  has  followed 
such  efforts,  as  the  chain  slides  over  much  of  the  vegetation 
without  killing  it.  A  springtooth  harrow  is  rather  effective 
in  small  laterals  where  the  water  is  not  over  a  foot  deep,  but  has 
to  be  frequently  cleaned,  and  is  a  failure  in  larger  canals.  Brush 
scythes  wielded  by  hand  can  also  be  successfully  employed  in 
small  laterals. 

The  most  effective  weapon  in  large  canals  is  the  submarine 
saw,  which  consists  of  a  flexible  steel  tape  with  teeth  on  both 
edges,  and  is  pulled  back  and  forth  across  the  bottom  of  the 
canal  by  a  man  on  each  bank.  It  has  lead  weights  to  hold  it 
against  the  bottom,  and  a  rope  handle  is  attached  to  each  end. 
The  work  of  sawing  progresses  against  the  current  of  course, 
the  saw  is  operated  at  an  angle  of  about  30  degrees  to  the  cross- 
section  of  the  canal,  and  the  pull  toward  the  upstream  end  does 
the  cutting.  The  vegetation  when  cut  rises  to  the  top  of  the 
water  and  floats  downstream,  where  it  is  taken  out  at  the  first 
bridge  by  one  or  two  men  with  pitchforks.  One  crew  can  pro- 
gress at  the  rate  of  from  1000  to  5000  feet  per  day.  The  cut- 
ting is  effective  at  the  time,  but  does  not  injure  the  roots,  which 
often  send  up  new  shoots  which  grow  rapidly  and  it  may  be 
necessary  to  repeat  the  process  two  or  three  times  in  a  season. 
This  method  is  not  effective  unless  there  is  enough  current  in 
the  canal  to  hold  the  plants  firmly  against  the  saw. 

Where  the  canal  is  free  from  stones  and  gravel  good  results 
may  generally  be  obtained  by  the  use  of  the  Acme  harrow,  or 
orchard  cultivator,  a  machine  consisting  of  long  parallel  blades 
attached  to  and  following  an  iron  frame,  with  the  sharp  edges 
of  the  blades  turned  to  a  horizontal  position.  It  cuts  the  roots 
just  below  the  surface  of  the  ground,  and  the  plants  float  to  the 
top  of  the  water  and  pass  downstream  to  the  first  structure 
where  they  are  removed  with  pitchforks.  The  cultivator  is 
drawn  by  means  of  long  chains,  by  a  team  on  each  bank  of 
the  canal.  By  adjusting  the  length  of  the  chains  the  machine 
can  be  made  to  work  on  either  side  or  bottom,  of  the  canal. 
Results  are  obtained  much  cheaper  with  this  method  than 
with  the  saw.  Where  there  is  a  tendency  to  silting  this  machine 


524  OPERATION  AND  MAINTENANCE 

stirs  up  the  silt  which  is  then  carried  along  and  deposited  upon 
the  land,  while  the  muddy  water  tends  to  retard  the  growth 
of  the  aquatic  plants,  and  helps  to  puddle  leaky  stretches  of 
the  canal.  Where  conditions  permit,  canal  velocities  of  2\  feet 
per  second  and  over  should  be  provided,  and  if  grades  sufficient 
for  this  cannot  be  secured,  it  may  be  advisable  to  provide  a 
canal  depth  of  5  feet  or  more,  remembering  that  the  narrow 
deep  canal  will  have  a  higher  velocity  on  a  light  grade  than  a 
shallower  one,  and  that  both  velocity  and  depth  tend  to  pre- 
vent trouble  with  aquatic  plants. 

The  narrow  deep  canal  having  a  higher  velocity  for  a  given 
grade,  and  deeper  water  for  a  given  capacity,  presents  for  both 
these  reasons  greater  security  against  the  growth  of  algae  or 
other  aquatic  plants. 

13.  Wind  Erosion. — New  canal  banks  built  of  sand  or  other 
light  soil  in  a  windy  country  are  often  attacked  by  wind,  and 
may  be  gradually  destroyed  unless  protected  in  time.  It  may 
be  necessary  to  provide  a  blanket  of  gravel  or  clay  if  these  are 
obtainable,  but  this  may  be  too  expensive,  and  in  any  case 
it  is  desirable  to  clothe  them  in  vegetation,  and  this  should  be 
undertaken  as  soon  as  possible  in  order  to  forestall  wind  erosion. 
The  natural  vegetation,  the  climate  and  the  soil  involved  should 
be  carefully  studied  and  in  many  cases  it  may  be  advisable 
to  sow  seeds  of  plants  that  will  grow  under  the  adverse  con- 
ditions, and  yet  not  become  a  nuisance.  In  most  parts  of  the 
West,  the  Russian  thistle  appears  spontaneously  after  a  time, 
unless  the  climate  is  too  dry  and  hot.  This  plant  protects  the 
soil  from  wind  erosion,  wherever  it  thrives,  but  becomes  itself 
a  nuisance  in  the  fall,  by  breaking  off  at  the  ground  and  blowing 
across  country  as  a  tumble  weed,  lodging  against  structures, 
clogging  turnouts  and  even  obstructing  the  canal  itself.  A 
pile  of  these  weeds  becoming  waterlogged  in  the  canal  will 
sometimes  collect  silt  and  other  drift,  thus  forming  bars  which 
reduce  the  capacity  of  the  canal,  and  perhaps  divert  the  current 
against  the  opposite  bank,  and '  start  erosion.  Nevertheless 
even  this  thistle  is  often  a  welcome  assistant  against  wind 
erosion,  on  account  of  its  persistence  where  nothing  else  will 


NOXIOUS  PLANTS  525 

grow.  Rye  is  sometimes  sown,  furnishing  valuable  protection, 
and  reproducing  itself  under  rather  unfavorable  conditions. 
It  has  the  important  virtue  of  never  becoming  a  nuisance. 
Care  should  be  taken  to  avoid  semi-aquatic  vegetation  such 
as  willows  and  various  water-loving  grasses,  which  will  encroach 
upon  the  water  section  of  the  canal,  collect  sediment  and  gradu- 
ally reduce  the  capacity  of  the  canal.  Some  of  these  plants 
are  very  difficult  to  check  and  control  when  once  started,  and 
are  most  apt  to  give  serious  trouble  in  canals  of  low  velocity. 

14.  Noxious  Plants. — It  is  not  always  possible  to  draw  a 
definite  line  between  plants  which  are  helpful  and  those  which 
do  more  harm  than  good.     In  general  the  control  of  weeds 
on  the  canal  banks  is  a  serious  matter,  and  a  constant  expense 
in  maintaining  the  canals  at  their  required  capacity. 

Various  methods  of  fighting  weeds  and  grasses  on  the  canal 
banks  are  employed,  such  as  mowing  them  frequently,  cutting 
below  the  ground  surface  with  hoes  or  shovels,  and  sometimes 
where  the  problem  is  most  difficult  sheep  and  goats  are  success- 
fully employed  by  confining  them  on  the  canal  banks  with 
fences.  They  must  be  furnished  in  sufficient  numbers  so  that 
they  will  be  constantly  hungry  and  keep  all  the  weeds  cropped 
close  to  the  ground,  otherwise  they  will  choose  those  they  like 
best,  and  let  others  grow.  This  method  has  been  successfully 
employed  in  Southern  Arizona,  New  Mexico  and  Texas  in 
controlling  Johnson  grass,  willows,  and  other  persistent  weeds. 

15.  Burrowing     Animals. — The    maintenance    of    a    canal 
system  is  a  perpetual  warfare  between  the  manager  and  a  horde 
of  burrowing  animals,  such  as  gophers,  ground   squirrels  and 
muskrats.     The  newly  built  banks  offer  favorite  locations  for 
their  holes,  and  where  one  emerges  on  the  canal  side  below 
the  water  line  the  water  follows  it  and   quickly-  enlarges  the 
hole  until  it  becomes  a  break  carrying  all  the  water  of  the  canal, 
and  sometimes  causing  great  damage  not  only  to  the  canal, 
but  to  the  irrigated  crops  and  to  the  land  itself.     One  of  the 
most  important  of  the  duties  of  the  canal  rider  is  to  scrutinize 
the   banks  for   signs  of  burrowing  animals  and  when  found, 
place  grain,  raisins,  or  other  food  thoroughly  soaked  in  poison 


526  OPERATION  AND  MAINTENANCE 

at  and  near  the  entrance  to  the  hole,  and  mark  the  spot  so 
that  it  can  be  readily  found  again. 

Various  forms  of  traps  have  been  devised  which  are  some- 
times employed  with  efficiency,  and  small  rifles  and  shotguns 
have  been  used.  It  is  absolutely  essential  that  these  pests 
be  held  in  check,  or  it  becomes  impossible  to  operate  the  system 
with  safety. 

1 6.  Land  Slides. — Where  a  canal  is  located  on  sidehill 
it  frequently  gives  trouble  in  inducing  land  slides.  These  may 
be  of  two  kinds.  On  a  hillside  where  the  natural  slope  is  steep, 
the  cutting  for  the  canal  may  remove  so  much  material  as  to 
leave  what  remains  in  an  unstable  situation,  with  a  tendency 
here  and  there  to  slide  into  the  canal. 

The  other  form  of  slide  is  that  resulting  from  the  saturation 
of  the  lower  bank  of  the  canal,  inducing  it  to  move  away  from 
the  canal  channel.  Both  types  of  slide  are  promoted  by  mois- 
ture, which  in  the  case  of  the  latter  is  furnished  by  the  canal, 
and  therefore  most  likely  to  happen  in  the  summer.  The 
first  type  or  upper  slide  is  more  likely  to  become  and  remain 
saturated  in  early  spring  while  snows  are  melting,  and  may 
therefore  occur  before  the  beginning  of  the  irrigation  season. 
In  fact,  a  full  canal  has  some  tendency,  by  its  weight  of  water, 
to  balance  and  retard  a  slide  from  above. 

Since  both  types  of  slide  are  promoted  by  saturation  of  the 
material,  it  follows  that  the  provision  of  good  drainage  is  in 
some  degree  a  remedy.  If  ponds  occur  above  the  canal  they 
may  have  a  tendency  to  promote  sliding,  and  drawing  them 
off  by  adequate  drainage  may  be  sufficient  to  prevent  this. 
The  same  may  be  said  of  any  system  of  surface  or  subsurface 
drainage  which  tends  to  prevent  the  saturation  of  the  material 
above  the  canal,  or  of  any  stratum  therein. 

The  probable  occurrence  of  slides  from  above  is  often  the 
factor  that  determines  the  infeasibility  of  building  and  main- 
taining a  canal  on  any  given  sidehill,  and  conditions  should  be 
carefully  studied  before  deciding  this  question. 

In  order  to  counteract  the  weakening  effect  of  the  cut  in  the 
material  it  may  be  advisable  in  some  cases  to  provide  a  canal 


LAND  SLIDES  527 

section  01  some  rigidity,  as  a  concrete  flume  or  pipe  which  can 
transmit  the  pressure  from  above  to  the  lower  bank,  and  to  the 
ground  under  tne  conduit,  which  thus  serves  as  a  retaining 
wall.  Such  a  device  was  employed  for  this  purpose  on  the 
Tieton  Main  Canal  (Fig.  119). 

Where  there  is  danger  of  sliding  of  the  lower  bank  this 
may  be  diminished  to  a  large  extent  by  lining  the  canal  with 
concrete,  and  for  this  reason  and  the  further  reason  that  the 
lined  canal  by  reason  of  diminished  friction  will  carry  the 
required  amount  of  water  with  less  cross-sectional  area,  and  will, 
by  preventing  seepage  save  valuable  water,  many  sidehill  canals 
are  lined  when  first  constructed,  and  many  others  are  lined 
later,  as  a  maintenance  precaution.  But  when  done  as  an 
afterthought,  there  is  loss  of  economy. 

The  character  of  the  soil  most  affected  by  saturation  is  clay, 
some  forms  of  which  become  semiliquid,  and  have  very  little 
stability  when  in  that  condition.  Certain  strata  on  which  the 
bank  rests  may  be  of  material  which  is  rather  porous  overlying 
other  strata  which  while  not  so  porous,  become  unstable  when 
saturated,  and  act  as  lubricants  on  which  the  overlying  bank 
can  readily  move.  If  these  strata  dip  down  the  hill,  we  have 
favorable  conditions  for  sliding,  and  it  may  be  that  they  make 
a  proposed  canal  location  infeasible,  and  that  it  will  be  neces- 
sary to  build  a  flume  or  tunnel  to  avoid  danger.  This  is  especi- 
ally true  where  the  location  is  above  a  railway  or  other  valuable 
property  that  would  be  damaged  by  a  canal  break.  In  doubt- 
ful cases  the  condition  may  be  materially  improved  by  providing 
deep  tile  drainage  to  prevent  saturation  of  the  treacherous 
material.  The  only  remedy  for  sliding  is  to  prevent  saturation. 

REFERENCES  FOR  CHAPTER  XX 

HARDING,  S.  T.  Operation  and  Maintenance  of  Irrigation  Systems.  McGraw- 
Hill  Book  Company,  New  York. 

NEWELL,  F.  H.     Irrigation  Management.     D.  Appleton  &  Co.,  New  York. 

BROWN,  HANBURY.  Irrigation,  its  Principles  and  Practice.  D.  Van  Nostrand 
Co.,  New  York. 


CHAPTER  XXI 
INVESTIGATION  OF  A  PROJECT 

1.  Reconnaissance. — To  investigate  the  feasibility  and  cost 
of  a  proposed  irrigation  project  it  is  necessary  to  consider  all 
the  various  factors  affecting  the  probability  of  the  existence 
of  a  feasible  project. 

First,  is  there  a  sufficient  area  of  good  land,  apparently 
accessible  to  the  water  supply?  If  this  seems  doubtful  it  may 
be  necessary  to  make  reconnaissance  surveys,  to  ascertain  how 
much  land  can  be  reached,  and  its  general  quality.  Before 
much  expenditure  is  incurred  for  this  purpose,  however,  inquiry 
should  be  made  into  existing  data  regarding  the  water  supply, 
for  if  this  is  scanty  or  precarious,  further  expenditure  may  be 
unwarranted. 

If  a  reconnaissance  shows  ample  good  land  fairly  smooth, 
an  apparent  water  supply  without  storage,  or  a  storage  site  if 
necessary,  with  no  obvious  insuperable  obstacles  in  the  way  of 
putting  the  water  on  the  land,  surveys  may  be  started  to  measure 
the  water  supply  and  determine  the  cost  of  controlling  and 
bringing  it  to  the  land. 

2.  Surveys. — Early   attention   should   be   given   the   water 
supply.     For  unless  a  long  record  of  stream  flow  kept  by  the 
government  is  available,  or  the  water  supply  is  a  great  river 
far  more  than  the  needs  of  the  project,  the  measurements  should 
begin  as  soon  as  possible,  for  they  must  continue  several  years 
to  be  a  safe  guide.     One  or  more  gaging  stations  should  be 
established,  and  continuous  record  kept. 

Students  of  water  supply  problems  are  often  misled  by 
formulae  for  computing  runoff  from  data  upon  rainfall,  evapora- 
tion, etc.,  put  forth  by  over-confident  authors,  or  derived  from 

528 


SURVEYS  529 

observations  of  totally  different  conditions.  Nothing  must 
be  allowed  to  take  the  place  of  actual  measurements  of  the 
stream. 

If  the  data  available  indicate  that  storage  will  be  necessary 
to  provide  a  sufficient  supply  of  water  when  needed,  the  existence, 
capacity  and  cost  of  storage  opportunities  must  be  carefully 
investigated.  If  these  are  wholly  or  partly  in  private  owner- 
ship liberal  allowance  must  be  made  for  their  purchase,  and  this 
is  an  expense  that  is  difficult  to  forecast,  and  is  commonly  under- 
estimated. Careful  examination  should  be  made  of  the  dam 
site,  especially  the  character  of  its  foundation  and  abutments 
and  the  available  material  for  construction.  The  amount  of 
sediment  carried  by  the  stream  should  be  considered  with 
reference  to  its  effect  on  the  life  of  the  reservoir,  and  if  con- 
siderable should  be  carefully  measured.  These  measurements 
can  usually  accompany  the  measurements  of  the  stream  and 
add  very  little  to  the  cost. 

A  topographic  survey  of  the  reservoir  site  or  sites  should  be 
made,  in  10  foot  contours  if  the  reservoir  is  deep,  and  closer 
intervals  for  shallow  reservoirs.  The  scale  may  be  2000  feet 
to  an  inch  for  very  large  reservoirs,  to  500  feet  to  an  inch  for 
small  ones. 

The  dam  site  should  be  mapped  on  a  scale  of  100  feet  to 
an  inch  or  larger,  in  5  foot  contours  if  precipitous  and  i  or 
2  foot  contours  if  the  slopes  are  .gentle. 

Careful  examination  should  be  made  of  the  rock  and  other 
material  with  reference  to  its  suitability  for  abutments  and 
foundation,  and  its  availability  for  construction  purposes.  If 
the  funds  are  available  and  construction  seems  probable  exami- 
nation by  means  of  test  pits  or  borings  should  be  undertaken. 
As  a  thorough  exploration  of  this  kind  is  expensive,  it  may  be 
wisest  to  confine  preliminary  investigations  to  a  few  test  pits 
at  first,  until  more  expenditure  appears  warranted. 

Examination  of  diversion  facilities  should  be  made  early, 
as  these  may  have  an  important  bearing  on  the  cost  and  feasi- 
bility. -It  is  desirable  to  divert  the  stream  at  such  an  eleva- 
tion that  the  canal  will  deliver  the  water  by  gravity  flow  along 


530  INVESTIGATION  OF  A  PROJECT 

the  upper  edge  of  the  land  to  be  irrigated.  This  may  be  some- 
times attained  by  a  diversion  sufficiently  upstream  to  achieve 
this,  or  if  the  grade  of  the  stream  is  moderate  and  good  dam  sites 
appear,  it  may  be  best  to  build  a  diversion  dam  of  considerable 
height  to  raise  the  water  to  the  necessary  elevation  and  lead 
the  canal  from  that  point.  In  this  way  heavy  canyon  con- 
struction may  sometimes  be  avoided.  Surveys  of  all  promising 
alternatives  should  be  made  and  compared  before  decision  is 
reached. 

Involved  in  the  above  alternatives  may  be  different  eleva- 
tions on  which  the  canal  may  be  located.  It  may  be  that  to 
command  all  the  irrigable  land  by  gravity  will  involve  an  undue 
amount  of  heavy  construction,  and  economy  will  require  a 
canal  location  on  lower  and  smoother  ground,  leaving  certain 
tracts  of  land  above  the  canal  to  be  abandoned  or  perhaps 
eventually  to  be  pumped  upon.  Trial  lines  may  be  run  to  test 
various  alternatives,  and  if  these  are  numerous  it  may  be  wise 
to  make  a  topographic  contour  map  of  the  country  under  study, 
on  which  all  alternatives  may  be  examined  before  making  any 
very  detailed  survey.  On  such  a  map,  such  alternatives  as 
those  of  tunnel  and  open  canal,  flume  and  inverted  siphon, 
and  the  like,  may  be  compared.  It  also  furnishes  the  preliminary 
information  for  planning  a  distribution  system. 

When  the  main  canal  line  is  decided  upon,  a  detailed  contour 
map  is  advisable  for  estimating  quantities.  On  this  map  the 
character  of  material  to  be  moved  should  be  shown,  whether 
rock,  shale,  sand  or  clay,  so  as  to  give  a  correct  indication  of 
the  probable  cost  of  excavation. 

This  detailed  map,  the  general  topography  map,  and  the 
borings  at  the  dam  site,  are  all  rather  expensive  details  that 
are  not  justified  unless  most  of  the  other  serious  doubts  of  the 
feasibility  of  the  project  have  been  removed.  A  detailed  soil 
survey  of  the  irrigable  land  is  to  be  desired  before  construction 
is  begun  so  as  to  determine  the  area  of  good  land  available,  and 
its  water  requirement.  However  attractive  the  water  supply 
and  the  engineering  features  of  the  project,  the  returns  must 
depend  on  the  area  and  fertility  of  the  lands  from  which  crops 


ESTIMATES  OF  COST  531 

may  be  secured.  This  information  is  therefore  just  as  important 
as  the  water  supply,  and  it  is  as  often  overlooked  or  over- 
estimated. 

The  character  of  the  crops  to  be  raised  and  their  market 
are  important  factors,  and  these  may  depend  upon  railroad 
facilities  to  a  large  extent.  All  these  must  therefore  be  given 
due  weight  in  estimating  prospective  returns. 

3.  Estimates  of  Cost. — At  every  stage  of  the  investigation 
it  is  necessary  to  make  tentative  estimates  of  cost,  for  com- 
parison of  alternatives,  for  elimination  of  unpromising  features, 
and  for  forecasting  the  ultimate  outcome,  so  that  unnecessary 
expenses  in  surveying  an  infeasible  project  may  be  avoided. 
These  preliminary  estimates  may  be  controlled  by  unit  prices 
adopted  for  all,  which  may  serve  their  purpose  fairly  well 
though  not  accurate,  provided  the  different  items  of  cost  bear 
the  correct  relations  to  each  other.  But  when  it  comes  to  the 
estimate  on  which  the  feasibility  depends,  it  is  important  that 
these  unit  prices  and  all  other  items  of  cost  be  not  only  relatively 
but  actually  as  accurate  as  possible,  and  this  presents  a  problem 
of  great  difficulty  in  many  cases. 

The  tendency  to  underestimate  construction  costs  is  nearly 
universal.  Even  in  the  construction  of  a  building  in  a  city, 
where  the  materials  and  processes  are  well  standardized,  labor 
conditions  are  stable  and  well-known  and  daily  experience 
furnishes  abundant  data  for  estimates,  the  owner  generally 
finds  when  his  house  is  finished  it  has  cost  more  than  he 
expected.  But  when  new  conditions  are  encountered,  and  the 
multitude  of  variations  in  materials,  transportation  and  labor 
conditions  are  involved,  this  tendency  is  greatly  intensified, 
and  nearly  always,  costs  exceed  the  estimates,  unless  great 
effort  is  made  to  make  these  liberal.  There  are  several  distinct 
causes  for  this  tendency  to  underestimate  costs. 

a.  Bias. — There  is  no  attempt  here  to  consider  dishonest 
estimates  made  with  a  deliberate  or  conscious  purpose  to 
present  an  attractive  showing  calculated  to  favorably  influence 
investors  regardless  of  the  facts.  We  are  now  dealing  with 
the  influences  that  bias  honest  effort.  Everyone  has  a  natural 


532  INVESTIGATION  OF  A  PROJECT 

desire  that  work  he  has  done  achieve  some  result.  The  investi- 
gations would  generally  not  have  been  started  except  for  the 
existence  of  a  strong  belief  that  a  feasible  project  would  be 
developed,  and  thus  exists  a  strong  if  unconscious  desire  that 
the  investigation  shall  result  favorably. 

b.  Influence. — There  frequently  exists  also,  a  strong  desire 
on  the  part  of  someone  interested  in  the  results,  who  is  in  touch 
with   the   inquiry,    who    continually   presents   arguments    and 
facts  favorable  to  cheap  construction  and  large  returns,  which 
are  likely  to  have  considerable  influence  on  the  most  judicial 
mind. 

c.  Inaccurate    Data. — The    estimator's    principal    guide    is 
previous  experience.     So  far  as  this  is  his  own,  and  intelligently 
used,  it  is  the  safest  possible  guide,  although  subject  to  the 
limitations   of   careful   and   discriminating   use.     But   usually, 
the  engineer  must  depend  less  upon  his  own  personal  experience 
than  upon  the  records  made  by  others,  and  here  he  is  upon 
dangerous    ground,    for    these    records    are    mostly    one-sided. 
Where  work  has  been  performed  very  cheaply,  it  is  the  subject 
of  boast  or   exploitation,  and  its   cheapness  is   often  greatly 
exaggerated  by  the  omission  of  such  charges  as  plant  cost, 
overhead,   preliminary  work,   etc.     Reports  of  unit  costs  are 
often  selected  from  the  most  favorable  periods  of  work,  thus 
omitting  expensive  delays,  repairs  or  other  contingencies,  and 
may  thus  be  less  than  half  the  average  actual  cost.     Where 
reports   of   excessive   costs   accidentally   become   public,    they 
are  generally  accompanied  by  explanations  of  unusual  difficulties, 
abnormal  conditions,  storms,  accidents,  or  the  stupid  blunders 
of  someone  else;    contingencies  not   to  be  expected  again,  so 
that  large  or  even  average  costs  are  thus  discredited  and  atten- 
tion   focused    upon    those    that    are    the   minimum,    whether 
reliable  or  not.     For  these  reasons,  cost  data  are  often  very 
misleading. 

d.  Omissions. — One  of  the  commonest  errors  in  estimates  is 
the  omission  of  certain  elements  of  cost,  owing  to  the  inherent 
difficulty  of  foreseeing  everything.     This  applies  not  only  to 


ESTIMATES  OF  COST  533 

unforeseeable  expenses  but  those  which  could  be  easily  fore- 
seen but  were  overlooked  or  forgotten. 

For  these  reasons,  the  beginner  should  understand  that  the 
path  of  the  estimator  is  beset  with  pitfalls  which  he  must  be 
careful  to  avoid,  and  he  should  be  cautious  about  accepting 
current  opinions  or  even  published  records  of  cost  until  these 
have  been  verified  and  their  completeness  and  reliability 
established. 


CHAPTER  XXII 
SPECIFICATIONS 

IT  is  important  to  have  clear,  concise  specifications  cover- 
ing engineering  work  required,  and  they  should  be  as  specific 
as  conditions  will  permit,  leaving  a  minimum  of  discretion 
with  the  engineer.  The  important  points  are  to  cover  the 
subject  thoroughly,  and  avoid  ambiguity  or  possibility  of  more 
than  one  obvious  meaning.  The  samples  here  given  are  in  the 
main  those  evolved  by  fifteen  years'  experience  on  large  works 
by  the  U.  S.  Reclamation  Service,  and  their  provisions  have 
been  thoroughly  tested.  It  is  not  intended,  however,  that  they 
be  used  without  modification,  but  only  as  a  guide  for  drawing 
specifications  adapted  to  local  conditions  in  each  case. 

The  above  applies  especially  to  work  let  by  contract,  for 
which  written  specifications  are  obviously  necessary.  It  has 
also  been  found  advisable,  on  large  works,  where  construction 
is  performed  by  the  direct  method  of  hired  labor  without  the 
intervention  of  a  contractor,  to  draw  similar  specifications 
for  the  guidance  of  the  engineer  in  charge  and  his  subordinates, 
where  the  superintendent  of  construction  occupies  a  position 
in  authority  similar  to  that  of  a  contractor,  and  although  under 
the  orders  of  the  engineer,  is  held  independently  responsible 
for  the  construction  forces  and  their  work.  In  this  manner  the 
Lahontan  Dam  in  Nevada,  and  the  Arrowrock  Dam  in  Idaho 
were  built.  The  specifications  of  the  latter  are  given  as  a 
sample  of  how  this  work  was  performed.  There  are  also  pre- 
sented standard  specifications  for  some  of  the  most  important 
work  required  in  irrigation. 

534 


SPECIFICATIONS  FOR  ARROW  ROCK  DAM  535 


SPECIFICATIONS  FOR  ARROWROCK  DAM 

GENERAL  PROVISIONS 

1.  The  Requirement. — The  purpose  of  the  work  covered  by  these  specifications 
is  the  construction  of  a  masonry  dam  and   its  appurtenant  features  across  the 
Boise  River  at  Arrowrock,  in  section    13,  T  3  N,  R  4  E,  about  20  miles  east  of 
Boise,  Idaho. 

2.  List  of  Drawings. 

1.  (14,302)  General  map  and  plan  of  construction  works. 

2.  (14,303)  Cross-section  of  dam. 

3.  (14,304)  Plan  of  dam. 

4.  (14,305)  Elevation  of  developed  upstream  face  of  dam. 

5.  (14,306)  Plan  and  sections  of  spillway. 

6.  (14,307)  Typical  sections  of  diversion  tunnel. 

7.  (14,308)  Cross-sections  of  north  wing  walls  at  tunnel  inlet  and  outlet. 

8.  (14,309)  Cross-sections  of  south  wing  walls  at  tunnel  inlet  and  outlet. 
Q.  (14,310)  Cross-sections  of  cofferdams. 

3.  Organization. — The  work  covered  by  these  specifications  is  authorized  by 
the  Secretary's  order  dated  January  7,  1911,  and  shall  be  done  with  Government 
forces.     The  Director  of  the  Reclamation  Service,  through  the  supervising  and 
construction   engineers    and    superintendent    of    construction,    will   purchase   all 
materials,  equipment  and  supplies  and  will  employ  all  labor  necessary  for  the  con- 
struction and  completion  of  the  dam  and  its  appurtenant  features.     A  scale  of 
wages  shall  be  fixed  from  time  to  time  by  the  supervising  engineer,  after  having 
received  suitable  written  recommendations  covering  such  scale  of  wages  from  the 
construction    engineer    and    superintendent    of    construction.     The    supervising 
engineer  shall  divide  the  organization  as  would  be  done  if  the  work  were  to  be  per- 
formed by  contract,  into  the  engineering  division,  under  the  direction  of  the  con- 
struction engineer,  and  the  construction  division,  under  the  direction  of  the  super- 
intendent of  construction. 

The  duties  of  the  engineering  division  shall  be  similar  to  those  of  the  engineering 
force  on  contract  work;  the  principal  duties  of  this  division  being  to  make  esti- 
mates and  designs  for  the  works  and  to  see  that  the  works  are  built  in  accordance 
with  the  plans  and  specifications,  and  this  division  will  be  held  strictly  responsible 
for  this  feature  of  the  work.  This  division  shall  also  give  the  construction  division 
such  help  as  may  be  necessary  in  getting  out  designs  and  estimates  for  the  construc- 
tion plant.  For  the  purpose  of  executing  his  duties,  the  construction  engineer 
shall  organize  office  and  field  engineering  corps  that  shall  report,  directly  to  him. 
All  work,  other  than  clerical,  in  connection  with  the  construction,  maintenance 
and  operation  of  the  Arrowrock  Railroad,  the  power  house  at  the  Boise  River 
Diversion  Dam  and  the  transmission  line  leading  therefrom  to  Arrowrock  shall 
be  under  the  charge  of  the  construction  engineer. 

The  duties  of  the  construction  division  shall  be  similar  to  those  of  the  con- 
struction force  on  contract  work;  the  principal  duties  of  this  division  being  to  pro- 
vide methods  and  plans  for  actually  executing  and  building  the  works  and  to 
construct  the  work.  This  division  will  be  held  particularly  responsible  for  the 


536  SPECIFICATIONS 

progress  and  cost  of  the  work.  In  any  work  on  designs  and  estimates  for  the 
construction  plant  that,  under  contract  work,  would  be  done  by  the  contractor's 
engineering  forces,  the  construction  division  shall  be  assisted  as  much  as  may  be 
necessary  by  the  engineering  division.  The  superintendent  of  construction  shall 
select  his  foremen  and  principal  assistants,  who  shall  report  to  him,  and  he  will 
be  held  responsible  for  the  efficiency  of  the  entire  construction  force.  He  shall 
detail  one  man  as  costkeeper,  who  shall  obtain  from  the  clerical  and  engineering 
forces  all  data  necessary  for  compiling  the  required  reports  of  costs.  At  the  end 
of  each  calendar  month  the  costkeeper  shall  furnish  the  construction  engineer 
(with  a  copy  to  the  supervising  engineer)  a  detailed  statement,  certified  by  the 
superintendent  of  construction  of  all  costs,  including  estimated  apportionment 
of  general  expenses,  depreciation,  unit  costs  of  work  done,  etc. 

The  supervising  engineer's  office  at  Boise  shall  handle  all  advertisements,  pur- 
chases and  vouchers  covering  materials  and  supplies  for  use  in  the  construction 
of  the  dam,  and  the  chief  clerk  of  the  supervising  engineer's  office  shall  be  responsible 
for  all  clerical  work.  He  shall  conduct  the  clerical  work  in  such  a  manner  as  to 
relieve  the  engineering  and  construction  divisions  from  the  necessity  of  occupying 
their  time  with  clerical  matters.  The  chief  clerk  shall  detail  any  clerks  who  may  be 
necessary  at  Arrowrock  or  other  points  on  the  Storage  Unit,  and  these  employees 
shall  be  responsible  to  him  in  connection  with  clerical  matters,  but  shall  be  sub- 
ject to  the  orders  of  the  construction  engineer  or  superintendent  of  construction 
in  connection  with  administrative  matters.  Pay  rolls  shall  be  made  up  in  the  super- 
vising engineer's  office,  based  on  time  books  certified  by  the  superintendent  of 
construction  and  transmitted  from  Arrowrock,  and  the  fiscal  agent  at  Boise  will 
pay  all  employees,  including  those  receiving  time  checks. 

4.  Reports  and  Estimates, — At  the  end  of  each  calendar  month  the  engineer 
shall  make  an  approximate  estimate  of  the  work  done  to  that  date,  and  these  esti- 
mates shall  be  prepared  with  the  same  degree  of  completeness  as  would  be  required 
in  the  case  of  contract  work.     As  soon  after  the  end  of  each  calendar  month 
as  possible,  a  complete  approximate  cost  report  shall  be  prepared  as  outlined  in 
paragraph  3  and  transmitted  to  the  supervising  engineer's  office  with  the  con- 
struction engineer's  regular  monthly  report.     Upon  the  completion  of  each  feature, 
a  detailed  report  of  that  feature  shall  be  prepared  and  shall  include  a  complete 
history  of  the  feature  and  a  final  estimate  of  quantities  with  total  and  unit  costs. 

5.  Progress  of  Work. — Work  shall  be  commenced  on  such  features  as  wagon 
roads,  telephone  lines,  etc.,  within  thirty  days  after  the  authorization  of  construc- 
tion, and  the  work  on  main  features,  the  dam  and  its  appurtenant  structures, 
will  be  begun  as  soon  thereafter  as  practicable.     The  diversion  works  will  be  com- 
pleted to  such  extent  that  water  may  be  diverted  from  the  present  river  channel 
immediately  after   the  June   floods  in   1912.     Work  of  excavation  in  the  river 
channel  shall  then  be  begun  and  the  work  will  be  prosecuted  with  all  practicable 
speed  until  the  concrete  in  the  dam  shall  have  been  placed  to  about  elevation 
3000.     After  that  time  the  rate  of  progress  shall  be  as  great  as  is  consistent  with 
proper  economy,  and  as  the  apportionment  of  funds  will  permit. 

6.  Cement. — All  Portland  cement  shall  be  purchased  through  the  cement  expert 
of  the  U.  S.  Reclamation  Service  at  Denver,  Colorado,  and  shall  be  inspected  under 
his  direction  before  shipment.    The  same  care  shall  be  observed  in  the  unloading, 
storing,  and  safe  keeping  of  the  cement,  and  for  the  return  of  the  full  number  of 


SPECIFICATIONS  FOR  ARROW  ROCK  DAM  537 

cement  sacks  to  the  railroad  station  in  serviceable  condition,  as  is  used  on  Construc- 
tion work  under  contract.  Upon-the  delivery  of  the  Portland  cement  at  the  dam 
site,  it  shall  be  reground  with  granite  or  other  suitable  material  to  form  sand- 
cement,  which  shall  be  used  throughout  the  dam,  spillway  weir,  and  lining,  in  the 
same  manner  as  Portland  cement,  unless  otherwise  specifically  ordered  by  the 
engineer.  Hereafter  in  these  specifications  the  term  "  sand-cement  "  will  signify 
the  product  of  regrinding  Portland  cement  with  suitable  blending  material  in  pro- 
portions fixed  by  the  chief  engineer,  and  these  proportions  shall  be  one  part  sand 
to  one  part  cement  by  weight,  unless  otherwise  directed  by  him.  All  sand-cement 
shall  be  inspected  and  tested  before  being  used  in  this  work. 

7.  Electric  Power  Plant. — The  United  States  will  build  and  operate  a  aooo-H.P. 
hydro-electric  power  plant  at  the  Boise  River  Diversion  Dam,  about  14  miles  west 
of  Arrowrock,  together  with  the  necessary  transmission  lines  for  furnishing  power 
for  construction  purposes  at  the  dam  site.    So  far  as  may  be  possible  and  economi- 
cal, all  construction  machinery  shall  be  operated  by  electrical  power.     This  power 
plant  will  not  be  completed  and  in  operation  until  about  June  i,  1912,  but  electric 
power  purchased  in  the  local  market  will  be  available  for  construction  purposes 
at  the  dam  about  October  i,  1911.     A  fair  rate,  to  be  determined  by  the  super- 
vising engineer,  for  the  power  used  from  this  plant,  shall  be  charged  against  the 
work  at  the  dam,  and  the  power  plant  will  be  given  a  corresponding  credit. 

8.  Steam  Railroad. — The  United  States  will  build  and  operate  a  standard  gage 
steam  railroad  between  Arrowrock  and  Barberton,  Idaho,  connecting  at  the  latter 
point  with  the  Barberton  branch  of  the  Oregon  Short  Line  Railroad.     This  road 
will  be  in  operation  by  November  15,  1911.     Freight  rates  on  this  line  shall  be 
established  from  time  to  time,  by  the  supervising  engineer. 

9.  Telephone  Lines. — Telephone  lines  will  be  built  and  operated  by  the  United 
States  between  Arrowrock  and  Boise,  Idaho,  and  will  be  ready  for  service  about 
May  i,  1911. 

10.  Wagon  Roads. — About  25  miles  of  wagon  roads  will  be  built  by  the  United 
States  to  replace  roads  that  will  be  flooded  by  the  Arrowrock  Reservoir  and  for 
various  other  purposes.     Some  of  these  roads  will  be  of  service  in  hauling  lumber 
and  other  materials  and  supplies.     The  location  of  these  roads  is  shown  in  drawing  i . 

11.  Construction  Camp. — A  construction  camp  to  accommodate  about  800  men 
will  be  built  and  maintained  at  Arrowrock  by  the  United  States,  and  the  sanitary 
conditions  at  this  camp  shall  be  kept  at  a  high  degree  of  excellence  at  all  times. 

12.  Sawmill.' — The  United  States  will  build  and  operate  a  sawmill  in  the  Boise 
National  Forest  about  16  miles  east  of  Arrowrock  and,  as  far  as  may  be  feasible 
and  economical,  all  lumber  needed  in  the  construction  of  the  dam  and  its  appur- 
tenant features,  including  the  construction  cam'--    shall  be  manufactured  at  this 
mill. 

GENERAL  FEATURES 

13.  Description. — The  work  contemplated  under  these  specifications  consists 
of  constructing  a  storage  reservoir  with  a  concrete  masonry  dam  and  a  concrete 
masonry  spillway,  together  with  the  incidental  work  of  excavating  and  construc- 
ting diversion  works. 

The  dam  will  be  a  gravity  type,  concrete  dam,  curved  in  plan.     It  will  be  about 
1050  feet  long  on  top  and  its  maximum  height  will  be  about  350  feet  above  the 


538  SPECIFICATIONS 

deepest  part  of  the  excavation.  The  lowest  portions  of  the  foundation  will  be 
about  80  or  90  feet  below  the  present  bed  of  the  river. 

The  spillway  will  consist  of  a  concrete  weir  about  400  feet  long,  discharging 
into  a  channel,  to  be  cut  in  the  hillside.  This  channel  will  convey  the  water  around 
the  north  end  of  the  dam  and  will  discharge  into  Deer  Creek. 

The  diversion  works  will  consist  of  two  crib  cofferdams  across  the  Boise  River 
and  a  tunnel  about  490  feet  long,  with  a  cross-sectional  area  of  about  670  square 
feet  and  a  capacity  of  about  20,000  second-feet,  having  an  inlet  bell  mouth  about 
90  feet  long  and  an  outlet  bell  mouth  about  150  feet  long. 

EXCAVATION  OF  TUNNELS 

14.  Description  of  Diversion  Tunnel. — The  tunnel  will  be  located  in  rock  for  its 
entire  length,  and  for  the  greater  part  will  be  in  firm,  hard  granite.     Pockets  of 
loose  lava  rock  may  be  encountered  but  it  is  expected  that  such  pockets  will  be  of 
small  extent.     Where  the  nature  of  the  rock  makes  it  necessary  the  sides  and  roof 
of  the  tunnel  shall  be  supported  by  suitable  timbering  and  lagging.     All  expense 
of  such  timbering  shall  be  classed  as  timber  lining,  but  the  cost  of  the  lagging 
shall  be  charged  to  excavation.     As  the  tunnel  is  to  be  lined  with  concrete  on  the 
bottom  and  sides  and  with  timber  above  the  springing  line  of  the  arch,  special  care 
shall  be  exercised  to  reduce  the  overbreak  to  a  minimum  and  to  have  the  exposed 
rock  in  good  condition,  free  from  cracks  and  other  objectionable  defects. 

15.  Classification  of  Material  in  Diversion  Tunnel. — All  material  excavated  for 
the  diversion  tunnel  between  stations  1+50  and  6  +  20  and  within  the  limits  of  the 
required  cross-section  as  shown  in  the  drawings  shall  be  measured  and  estimated 
in  cubic  yards  and  classified  as  follows: 

Heading  and  Arches. — All  material  above  the  springing  line  of  the  arch. 
Bench. — Alt  material  below  the  springing  line  of  the  arch. 

1 6.  Shaft. — A  shaft  about  6  feet  square  for  use  in  refilling  the  tunnel  shall  be 
driven  as  directed  by  the  engineer.     As  this  shaft  will  also  be  refilled  with  concrete, 
it  shall  be  of  the  smallest  cross-section  practicable.     The  excavation  of  this  shaft 
shall  be  measured  and  estimated  by  the  linear  foot. 

17.  Cut-off  Tunnel. — A  cut-off  tunnel  shall  be  driven  along  the  line  of  contact 
between  the  lava  and  granite  and  shall  later  be  filled  with  concrete.     This  tunnel 
shall  be  of  the  smallest  practicable  dimensions  and  the  excavation  of  the  same  will 
be  measured  and  estimated  by  the  linear  foot. 

EXCAVATION  FOR  DAM,  SPILLWAY,  TUNNEL  PORTALS  AND  COFFERDAMS 

1 8.  Description. — The  excavation  for  the  dam  will  cover  all  excavation  required 
to  obtain  a  suitable  foundation  for  the  dam,  including  excavation  for  keyways, 
cut-off  trenches,  steps  or  benches,  unless  such  excavation  is  included  under  special 
preparations  of  rock  foundations  for  dam  as  outlined  in  paragraph  46.     The  mate- 
rial in  the  river  channel  consists  mainly  of  river  sand,  gravel,  and  boulders,  and 
constitutes  the  greater  part  of  the  material  to  be  excavated  for  dam  foundation. 
On  the  south  side  of  the  river,  the  excavation  will  consist  of  stripping  the  dam  site 
of  a  shallow  covering  of  loose  material  and  cutting  suitable  foundation  in  the  rock. 
The  work  on  the  north  abutment  will  consist  mainly  of  removing  a  mass  of  seamy 
rock  and  large  boulders  embedded  in  loose  rock  and  loam,  and  of  cutting  a  suit- 
able foundation  in  the  ledge  rock. 


SPECIFICATIONS  FOR  ARROW  ROCK  DAM  539 

The  greater  part  of  the  material  to  be  excavate:!  for  the  spillway  consists  of 
granite  rock,  covered  by  a  shallow  layer  of  loam  and  sand. 

The  excavation  for  the  tunnel  portals  will  cover  all  excavation  required  for  the 
inlet  and  outlet  bell  mouths  and  not  included  in  the  tunnel  proper.  The  material 
consists  of  a  lava  rock  talus  overhang  sand,  gravel,  boulders,  and  ledge  rock. 

The  excavation  for  the  cofferdams  will  consist  of  excavating  the  river  bottom 
to  a  level  bed  and  excavating  cut-off  trenches  at  the  abutments  on  the  north  side 
of  the  river. 

19.  Classification. — All  excavation  for  the  dam,  spillway,  tunnel  portals  and 
cofferdams  shall  be  measured  and  estimated  by  the  cubic  yard  under  the  following 
•classes: 

Dry  Excavation. — All  material  excavated  above  elevation  2960,  which  is  about 
the  mean  low  water  level  of  the  Boise  River. 

Wet  Excavation. — All  material  excavated  below  elevation  2960. 

The  classifications  of  material  shall  be  the  same  under  each  of  the  above  desig- 
nations and  shall  be  as  follows: 

Loose  Material. — The  excavation  of  loose  material  shall  include  the  excava- 
tion and  disposal  of  all  loam,  sand,  gravel,  mud,  loose  rock,  and  all  other  mate- 
rial not  included  in  rock  excavation,  except  as  hereinafter  specified  under  Para- 
graph 46. 

Rock  Excavation. — Rock  excavation  shall  include  the  excavation  and  disposal 
of  all  solid  rock  removed  by  blasting,  boulders  of  one-half  a  cubic  yard  or  more 
in  volume,  and  all  rock  removed  by  barring  and  wedging.  Wherever  the  excava- 
tion consists  of  a  large  proportion  of  boulders  of  one-half  a  cubic  yard  or  more  in 
volume  occurring  in  gravel,  earth,  or  loose  rock,  as  is  the  case  near  the  river  level 
on  the  north  side  of  the  river  channel,  the  amount  of  "  rock  excavation  "  may  be 
estimated  as  a  percentage  of  the  total  excavation  if  deemed  advisable  by  the  engi- 
neer. 

20.  Rock  Excavation  for  Foundations. — Rock  shall  be  excavated  to  a  sufficient 
depth  to  secure  a  foundation  on  sound  ledge  rock,  free  from  open  seams  or  other 
objectionable  defects.     It  is  the  intention  to  build  the  masonry  against  the  sides 
of  these  rock  excavations.     To  preserve  the  rock  outside  the  lines  of  the  excava- 
tion in  the  soundest  possible  condition  and  to  obtain  over  the  whole  foundation 
a  rock  surface  free  from  open  seams  or  cracks,  unusual  precautions  shall  be  used  in 
excavating.     Rock  excavation  may  be  done  by  blasting  to  the  extent  directed  by 
the  engineer,  with  explosives  of  such  moderate  power  and  in  such  positions  as  will 
neither  crack  nor  damage  the  rock  outside  of  the  prescribed  limits  of  the  excava- 
tion;   and  whenever,  in  the  opinion  of  the  engineer,  further  blasting  is  liable  to 
injure  the  rock  upon  or  against  which  the  masonry  is  to  be  built,  blasting  shall  be 
discontinued  and  the  excavation  of  the  rock  continued  by  wedging  and  barring, 
or  other  approved  methods. 

21.  Preparation  of  Rock  Foundations. — The  surfaces  of  the  rock  foundations 
shall  be  left  sufficiently  rough  to  bond  well  with  the  masonry  and,  if  required  by 
the  engineer,  shall  be  cut  into  rough  benches  or  steps,  and  great  care  shall  be  taken 
not  to  open  or  break  the  ledge  rock  unnecessarily  in  doing  this  work.     Before  laying 
the  masonry  on  or  against  the  ledge  rock,  the  latter  shall  be  scrupulously  freed 
from  all  dirt,  gravel,  scale,  loose  fragments,  and  other  objectionable  substances 
by  means  of  jets  of  water,  air,  or  steam  under  effective  pressure,  or  of  stiff  brooms 


540  SPECIFICATIONS 

hammers  and  other  effective  tools.  Steam  jets  shall  be  used  to  remove  thoroughly 
any  ice  or  snow  that  may  be  on  the  ledge  rock  when  it  is  desired  to  lay  masonry. 
All  springs  shall  be  piped  and  grouted  in  a  satisfactory  manner.  After  cleaning 
and  before  concrete  is  laid  on  or  against  the  ledge  rock  the  water  shall  be  removed 
from  the  depressions  so  that  the  surface  can  be  inspected  to  determine  whether 
seams  or  other  defects  exist.  All  expense  of  preparing  rock  foundations  except  as 
hereinafter  stated  in  paragraphs  44,  45,  and  46  shall  be  included  in  the  cost  of 
"  rock  excavation." 

GENERAL  REQUIREMENTS  FOR  CONCRETE 

22.  Composition. — All  concrete  shall  be  composed  of  cement,  sand,  gravel  and 
water,  or  cement,  sand,  gravel,  water  and  cobblestones,  in  the  proportions  fixed 
by  the  construction  engineer  for  the  character  or  work  in  hand.     The  cement  used 
will  in  general  be  sand  cement,  but  in  the  diversion  works  and  in  other  special  cases 
when  directed  by  the  engineer.     Portland  cement  may  be  used. 

23.  Sand. — The  sand  used  in  concrete  shdl  be  of  a  quality  satisfactory  to  the 
construction  engineer,  shal1  be  free  from  organic  matter,  and  shall  not  contain  more 
than  10  per  cent  by  weigh    of  clay  or  other  foreign  matter.     The  particles  of  sand 
shall  be  well  graded,  ana  the  coarsest  particles  shall  not  be  larger  than  those  that 
will  pass  a  screen  having  f-inch  square  holes      The  sane   shall  be  of  the  best 
quality  obtainable  at  reasonable  cost  in  the  vicinity  of  the  work. 

24.  Gravel. — The  gravel  used  in  the  concrete  shall  be  either  clean,  hard,  broken 
rock,  or  clean,  screened  gravel  and  shall  be  well  graded  and  of  such  sizes  as  will 
pass  a  grizzly  having  bars  set  3  inches  apart  and  will  be  retained  on  a  screen  hav- 
ing | -inch  square  holes. 

25.  Cobblestones. — Cobblestones  used  in  the  concrete  shall  be  sound,  clean 
gravel  or  broken  rock  of  such  size  as  will  pass  a  grizzly  having  bars  set  about 
6  inches  apart  and  be  retained  on  a  grizzly  having  bars  set  3  inches  apart. 

26.  Water. — The  water  used  for  the  concrete  shall  be  reasonably  clean  and  free 
from  objectionable  quantities  of  organic  matter,  oil,  grease,  or  other  like  impurities. 

27.  Mixing. — The  sand,  gravel,  cobbles,  and  cement  shall  be  mixed  and  the 
quantity  of  \vater  added  shall  be  such  as  to  produce  a  homogeneous  mass  of  uni- 
form  consistency.     Except   in   cases   of   emergency   when   small   quantities   are 
needed,  the  concrete  shall  be  mixed  by  one  of  the  standard  "  batch  ''  machine 
mixers.     Whenever  any  machine  fails  to  perform  the  mixing  thoroughly,  it  shall 
be  made  satisfactory  or  removed  and  another  machine  substituted.     When  from 
any  cause  resort  to  hand  mixing  is  necessary,  the  mixing  shall  be  done  in  a  thorough 
and  satisfactory  manner.     Concrete  shall  be  mixed  "  wet  "  wherever  practicable 
and  "  dry  "  only  when  the  nature  of  the  work  renders  such  use  unavoidable. 

28.  Placing. — The  concrete  shall  be  handled  in  such  a  manner  that  initial  set 
or  the  separation  of  the  ingredients  before  depositing  shall  be  avoided.     Should 
separation  occur,  the  concrete  shall  be  thoroughly  remixed.     Xo  concrete  that  has 
received  its  initial  set  Ibefore  being  deposited  shall  be  used  in  the  work  and  any 
such  mixture  shall  be  immediately  removed  from  the  vicinity  of  the  work.     All 
surfaces  upon  which  concrete  is  laid  shall  be  cleaned  as  specified  or  directed  and 
thoroughly  wet  immediately  before  concrete  is  deposited.     If  so  directed,  a  bed 
of  fresh  mortar  of  the  thickness  required  or  a  thin  coat  of  grout  shall  be  spread 


SPECIFICATIONS  FOR  ARROW  ROCK  DAM  541 

over  the  foundation  and  thoroughly  worked  into  all  depressions  and  crevices. 
Under  no  circumstances  shall  concrete  be  laid  in  deep,  moving,  or  muddy  water. 
All  exposed  faces  of  concrete  work  shall  be  moulded  against  steel  forms,  or,  if 
timber  forms  are  used,  against  lagging  that  has  been  sized  to  uniform  thickness 
and  placed  so  as  to  prevent  leakage  of  the  fluid  concrete.  All  forms  shall  be  accu- 
rately and  rigidly  placed  to  conform  to  the  lines  established  by  the  engineer. 
The  bracing  and  tying  devices  must  have  sufficient  strength  and  stiffness  to  with- 
stand the  pressure  of  fluid  concrete  without  springing  or  warping.  The  con- 
crete shall  be  placed  against  these  forms  and  so  manipulated  by  spading  and 
tamping  as  to  secure  a  body  of  concrete  having  the  maximum  possible  density  and 
showing  smooth  and  uniform  faces.  Where  the  use  of  contraction  joints  is  speci- 
fied for  the  separation  of  adjoining  masses,  the  expense  of  constructing  all  such 
joints  shall  be  included  in  the  cost  of  placing  concrete. 

2Q.  Building  Neiv  Concrete  on  Old. — In  order  to  insure  a  thorough  bonding  and 
a  perfect  joint  between  fresh  concrete  and  that  which  has  set,  such  provision  shall 
be  made  of  steps,  dovetails  or  other  devices  or  methods  as  may  be  prescribed. 
Whenever  fresh  concrete  and  concrete  that  has  set  are  joined,  the  contact  sur- 
faces of  the  old  concrete  shall  be  thoroughly  roughened  and  cleaned,  and  it  shall 
be  clean  and  wet,  but  free  from  pools  of  water,  at  the  moment  the  fresh  con- 
crete is  placed.  If  directed,  a  bed  of  fresh  mortar  or  a  coat  of  grout  shall  be 
applied  to  the  contact  surfaces  of  the  old  concrete  and  thoroughly  worked  into 
all  depressions  and  crevices.  Special  efforts  shall  be  made  to  remove  very 
thoroughly  all  laitance  and  other  substances  which  would  prevent  complete 
cohesion  of  the  concrete  throughout  the  main  body  of  the  dam. 

30.  Laying  Concrete  in  Freezing  Weather. — No  concrete  shall  be  laid  during 
freezing  weather  unless  special  precautions  are  taken  to  prevent  damage  from  freez- 
ing.    Whenever  concrete  is  laid  during  freezing  weather,  the  materials  of  the  aggre- 
gate shall  be  thoroughly  heated  to  remove  all  frost  and  warm  water  shall  be  used 
in  mixing.     No  frozen  materials  shall  be  used  in  making  concrete  and  no  concrete 
shall  be  allowed  to  freeze  in  any  part  within  ten  days  after  mixing  nor  shall  any 
concrete  be  built  upon  a  frozen  surface.  • 

31.  Embedded  Rock. — In  all  mass  concrete  having  a  thickness  of  15  inches  or 
more,  sound  and  clean  cobblestones  or  rock  fragments  of  a  size  that  can  be  lifted 
and  handled  by  one  man,  shall  be  incorporated  in  the  concrete.     The  proportion 
of  such  rocks  shall  be  as  nearly  uniform  throughout  as  practicable.     No  rock 
shall  be  laid  in  actual  contact  with  an  adjacent  one  or  wjthin  2  inches  of  the  forms. 
In  the  main  body  of  the  dam,  there  shall  be  placed  hard,  sound,  clean,  and  durable 
rocks  of  derrick  size,  carefully  shaken  to  position  in  fresh  beds  of  concrete.     When- 
ever possible,  smaller  rocks  shall  be  embedded  in  the  concrete  between  the  large 
rocks.     The  object  is  to  obtain,  especially  in  the  main  body  of  the  dam,  a  mono- 
lithic mass  of  stone  and  concrete  containing  as  large  a  proportion  of  rock  and  as 
impervious  to  water  as  it  is  practicable  to  secure.     Stones  to  be  used  as  embedded 
rock  wherever  used  shall  be  thoroughly  cleaned  before  being  brought  to  the  place 
where  they  are  to  be  used,  by  washing  with  water  under  pressure  from  a  nozzle, 
by  the  use  of  brushes,  or  as  otherwise  directed,  and  shall  be  satisfactorily  clean 
when  placed  in  the  concrete.     All  rock  shall  be  thoroughly  wet  at  the  time  of  plac- 
ing in  the  work. 

32.  Sprinkling. — During  all  of  the  year  except  the  colder  months,  all  concrete 


542  SPECIFICATIONS 

shall  be  kept  thoroughly  wet  by  sprinkling  with  water  until  the  concrete  shall  have 
become  thoroughly  set. 

33.  Finishing  Concrete  Surfaces. — Immediately  after  the  removal  of  the  forms, 
all  rough  surfaces  and  irregularities  of  exposed  work  shall  be  dressed  and  all  voids 
that  may  occur  shall  be  filled  with  mortar.     The  floors  of  the  spillway  and  diver- 
sion tunnel  shall  have  their  top  surface  finished  by  straight-edging  and  floating 
similar  to  a  sidewalk  finish,  except  that  the  standard  mixture  of  concrete  shall  be 
used  without  any  additional  surface  coat  of  mortar.     Such  surfacing  shall  be  done 
immediately  after  placing  the  body  of  the  concrete.     A  wash  of  thin  cement  grout 
shall  be  applied  to  all  exposed  surfaces  of  concrete  except  floors  and  similar  surfaces. 
The  outlet  conduits  shall  be  finished  smooth  and  particular  care  shall  be  taken  by 
hand  troweling  or  otherwise,  to  make  a  hard,  smooth,  surface. 

CONCRETE  FOR  SPILLWAY 

34.  Description. — The  concrete  work  in  the  spillway  will  consist  of  constructing 
of  mass  concrete  the  spillway  weir,  which  will  be  about  400  feet  long,  and  of  lining 
the  sides  and  bottom  of  the  spillway  trench  with  reinforced  concrete  and  of  con- 
structing the  roadway  and  parapet  walls  below  the  end  of  the  dam. 

35.  Classification. — All  concrete  placed  in  the  spillway  weir  shall  be  classed 
and  estimated  as  "  spillway  weir."     All  other  concrete  placed  in  the  spillway 
structure  shall  be  classed  and  estimated  as  "  spillway  lining." 

36.  Special  Foundation  of  Broken  Stone. — The  foundation  for  certain  portions 
of  the  concrete  used  in  the  spillway  lining  shall  be  a  layer  of  broken  stone,  not  less 
than  4  inches  thick  at  any  point,  thoroughly  rammed.     The  top  of  this  layer  of 
rock  shall  be  at  the  bottom  of  the  concrete  lining  as  shown  in  the  drawings.     This 
special  foundation  shall  be  measured  and  estimated  in  cubic  yards  on  a  basis  of  a 
6-inch  thickness,  unless  a  greater  depth  of  broken  stone  is  required  by  the  engi- 
neer, in  which  case  the  additional  rock  required  shall  be  measured  and  estimated. 
Details  of  this  work  are  shown  and  described  further  in  drawing  5. 

CONCRETE  FOR  DIVERSION  TUNNEL 

37.  Description. — The  bottom  lining  of  the  tunnel  will  consist  of  plain  concrete 
and  the  side  lining  will  consist  of  plain  concrete  suitably  bonded  to  the  rock  sides 
where  necessary  by  means  of  steel  bars.     The  inlet  and  outlet  wing  walls  will 
consist  of  concrete  lining  placed  on  the  rock  sides  and  suitably  bonded  thereto, 
and,  in  most  cases,  surmounted  by  a  concrete  wall  of  gravity  section.     The  inlet 
and  outlet  floors  will  consist  of  a  lining  of  plain  concrete  where  the  foundation  is 
ledge  rock  and  of  reinforced  concrete  where  the  foundation  is  sand  and  gravel. 
The  tunnel  refilling  will  consist  of  placing  mass  concrete  in  the  portion  of  the 
tunnel  underlying  the  foundations  of  the  dam.     All  expense  incurred  in  such 
refilling,  including  cofferdams,  and  bulkheads,  shall  be  charged  to  this  item. 

38.  Classification. — All  concrete  placed  as  lining  between  stations  1+50  and 
6+20  of  the  diversion  tunnel  shall  be  classed  and  estimated  as  "  diversion  tunnel 
lining."     All  concrete  placed  in  inlet  and  outlet  walls  and  portals  and  not  included 
as  tunnel  lining  shall  be  classed  and  estimated  as  "  diversion  tunnel  inlet  and 
outlet  wing  walls."     All  concrete  placed  in  the  floors  and  cut-off  walls  of  the  inlet 
and  outlet  and  not  included  in  tunnel  lining  shall  be  classed  and  estimated  as 


SPECIFICATIONS  FOR  ARROW  ROCK  DAM  543 

"  diversion  tunnel  inlet  and  outlet  floors."     All  concrete  placed  in  refilling    the 
tunnel  shall  be  classed  and  estimated  as  "  refilling  diversion  tunnel." 

39.  Refilling  Shaft. — The  shaft  shall  be  refilled  with  concrete  as  directed  by  the 
engineer.     This  refilling  shall  consist  of  mass  concrete  and  shall  be  measured  and 
estimated  by  the  cubic  yard. 

CONCRETE  FOR  COFFERDAMS 

40.  Classification  and  Description. — All  concrete  placed  in  the  cofferdams  shall  be 
classed  and  estimated  as  "  cofferdam  concrete."     This  item  consists  mainly  of 
plain  concrete  to  be  placed  in  the  core  walls  of  the  abutment. 

CONCRETE  FOR  CUT-OFF  TUNNEL 

41.  Classification  and  Description. — All  concrete  placed  in  refilling  the  cut-off 
tunnel  shall  be  classed  and  estimated  as  "  refilling  of  cut-off  tunnel." 

CONCRETE  FOR  DAM 

42.  Description. — It  is  planned  to  build  the  main  body  of  the  dam  of  concrete 
consisting  of  about  i  part  sand-cement,  2\  parts  sand,  5  parts  gravel  and  3  or  4 
parts  cobblestones,  in  which  large  rock  and  boulders  of  various  sizes  will  be  em- 
bedded.    These  proportions  may  be  varied  to  suit  conditions  as  they  may  develop. 
A  small  amount  of  reinforced  concrete  will  also  be  used. 

43.  Classification  and  Measurement. — All  concrete  in  the  dam  shall  be  classed 
and  estimated  under  one  item.     Deductions  shall  be  made  from  the  gross  volume 
for  the  space  occupied  by  the  inspection  tunnel  and  the  outlets,  but  no  deductions 
shall  be  made  on  account  of  the  drainage  system. 

SPECIAL  PREPARATION  OF  ROCK  FOUNDATION  OF  DAM 

44.  Description. — After  the  rock  foundation  for  the  dam  has  been  prepared 
as  outlined  in  paragraph  21  of  these  specifications,  all  further  work  on  said  founda- 
tion whether  shown  in  the  drawings  or  required  by  the  engineer,  shall  be  designated 
as  "  special  preparation  of  rock  foundation  of  dam,"  provided  such  further  work 
is  not  included  under  paragraph  28  of  these  specifications. 

45.  Classification. — Special  preparation  of  rock  foundations  of  dam  shall  be 
measured  and  estimated  under  the  following  classes: 

Areas  Receiving  Special  Preparation. — All  areas  receiving  special  preparation 
as  outlined  in  paragraph  46  shall  be  measured  and  estimated  by  the  square  yard 
and  at  least  5  square  yards  shall  be  allowed  for  any  area  on  which  such  special 
preparation  is  required. 

Pressure  Grouting. — All  pressure  grouting  as  outlined  in  paragraph  47  shall  be 
measured  and  estimated  by  the  barrel  of  cement  used  in  such  grouting. 

Drilling  Drainage  Holes  and  Main  Grout  Holes. — All  drilling  for  drainage  holes 
and  for  the  main  grout  holes  shown  on  the  drawings  and  not  included  under  para- 
graph 46  shall  be  measured  and  estimated  by  the  linear  foot  of  holes  drilled. 

46.  Areas  Receiving  Special  Preparation. — Portions  or  the  whole  of  the  founda- 
tions of  the  dam  .may  be  designated  for  special  preparation  and  in  all  areas  thus 
designated  seams  and  cavities  shall  be  traced  as  far  as  directed  by  the  engineer 
by  drilling  holes  or  by  other  approved  means.     All  such  seams  and  cavities  shall 
then  be  filled  with  concrete,  mortar,  or  grout.     Whenever  directed  by  the  engineer, 


544  SPECIFICATIONS 

grout  shall  be  pumped  under  pressures  required  by  him  through  hose  or  pipe  of 
at  least  2  inches  in  diameter,  and  the  connection  between  the  hose  or  pipe  and  the 
rock  shall  be  made  tight.  Such  grouting  does  not  include  grouting  the  main  grout 
holes  shown  in  the  drawings  and  described  under  paragraph  47. 

47.  Pressure  Grouting  and  Drilling  Drainage  Holes  and  Main  Grout  Holes. — In 
addition  to  the  drilling  and  pressure  grouting  that  may  be  required  under  paragraph 
46,  deep  grout  and  drainage  holes  shall  be  drilled  as  shown  on  the  drawings  or  as 
directed  by  the  engineer,  and  after  a  portion  of  the  masonry  in  the  dam  has  been 
placed,  grout  under  suitable  pressure  shall  be  pumped  into  the  grout  holes  as 
directed  by  the  engineer. 

STRUCTURAL  TIMBER 

48.  Description. — Structural  timber  will  be  required  for  the  upper  and  lower 
cofferdams,  for  portions  of  the  diversion  tunnel  inlet  and  outlet  wing  walls,  and  for 
the  timber  lining  for  the  roof  of  the  diversion  tunnel.     All  structural  timber  shall 
be  of  the  dimensions  shown  in  the  drawings,  free  from  loose  knots,  shakes,  or  other 
imperfections  that  impair  its  strength  for  the  uses  for  which  it  is  intended.     Unless 
otherwise  specified  or  required,  all  structural  timber  shall  be  of  pine  or  fir  obtained 
near  the  sawmill  mentioned  in  paragraph  12. 

49.  Measurement. — All  structural  timber  shall  be  measured  by  the  thousand 
feet  board  measure  in  place. 

COFFERDAMS  AND  TIMBER  WING  WALLS 

50.  Description. — The  upper  and  lower  cofferdams  and   the   timber  of  the 
diversion  tunnel  wing  walls  will  consist  of  timber  cribs  of  the  dimensions  shown  on 
the  drawings,  thoroughly  filled  with  loam,  sand,  gravel  and  rock  as  specified  in 
paragraph  53.     Longitudinal  timbers  shall  break  joints  and  shall  butt  only  at 
intersections  with  cross  timbers.     At  butting  joints,  two  drift  bolts  shall  be  placed 
in  the  end  of  each  butting  timber  and  at  all  other  intersections  the  timbers  shall 
be  secured  by  two  drift  bolts. 

TIMBER  LINING  IN  DIVERSION  TUNNEL 

51.  Description. — The  timber  lining  in  the  diversion  tunnel  will  consist  of  4  X  12- 
inch  planks  securely  spiked  to  i4Xi4-inch  timber  sets  as  shown  on  the  drawings. 
The  4 X i2-inch  planks  shall  be  of  Oregon  fir  or  other  suitable  material,  carefully 
dressed  to  the  required  thickness.     These  planks  shall  break  joints  and  butt  only 
at  intersections  with  the  timber  sets.     At  butting  joints  three  lo-inch  boat  spikes 
shall  be  placed  in  the  end  of  each  abutting  plank,  and  at  all  other  intersections  the 
planks  shall  be  secured  by  three  zo-inch  boat  spikes.     The  space  between  the  tim- 
ber sets  and  the  excavated  section  shall  be  thoroughly  filled  with  blocking  and 
lagging  as  directed  by  the  engineer.     All  cost  of  such  blocking  and  lagging,  not 
provided  for  in  paragraph  14,  shall  be  charged  to  the  cost  of  timber  lining. 

PILING 

52.  Description  and  Measurement. — Round  piles  and  sheet  piles  of  the  dimen- 
sions shown  in  the  drawings  will  be  required  in  the  construction  of  the  cofferdams. 
Round  piles  shall  be  measured  as  the  number  of  such  piles  actually  placed  in  the 
cofferdams..    Round  piles  shall  be  of  lengths  shown  on  the  drawings  and  shall 


SPECIFICATIONS  FOR  ARROW  ROCK    DAM  545 

be  cut  from  sound,  growing  timber  of  either  pine  or  fir,  straight  and  tape'ring, 
and  not  less  in  diameter  than  8  inches  at  the  smaller  end.  Sheet  piles  shall  be  made 
of  sound  fir  or  pine  timbers  of  the  size  and  lengths  required  with  strips  of  3X4- 
inch  timber  securely  spiked  on  two  opposite  sides  in  such  a  manner  as  to  form  a 
tongue  and  groove  on  each  pile.  Sheet  piles  shall  be  measured  and  estimated  under 
two  heads,  "  number  of  piles  driven  "  and  "  feet  board  measure."  The ."  number 
of  piles  driven  "  shall  include  only  the  number  of  piles  actually  driven  and  left  in 
the  cofferdams.  "  Feet  board  measure  "  shall  include  only  such  piles  as  are  driven 
and  left  in  the  cofferdams  but  shall  include  the  waste  by  cut-off  from  such  piles. 

ROCK  FILL 

53.  Description  and  Measurement. — Rock  fill  will  be  required  in  the  cofferdams 
and  in  the  crib  portions  of  the  tunnel  wing  walls.     It  shall  consist  of  rock  frag- 
ments of  varying  size,  sand,  gravel  and  loam  in  proportions  fixed  by  the  engineer, 
the  whole  mass  being  classed  as  rock  fill.     The  manner  of  placing  rock  fill  shall 
be  subject  to  the  approval  of  the  construction  engineer  and  will  vary  in  different 
parts  of  the  work,  but  wherever  practicable  the  voids  in  the  rock  fill  shall  be  filled 
with  the  fine  material  by  hydraulicking  this  material  compactly  in  place.     Rock 
fill  will  be  measured  in  place  and  estimated  by  the  cubic  yard. 

RIPRAP 

54.  Classification. — Riprap  will  be  classed  as  follows: 

Grouted  Riprap. — All  riprap  grouted  with  cement  grout  or  with  concrete. 
Plain  Riprap. — All  riprap  not  included  in  grouted  riprap. 

55.  Description. — Riprap  will  consist  of  rock  of  good,  hard  durable  quality, 
not  less  than  12  inches  in  thickness,  placed  upon  a  bed  of  gravel  or  broken  stone 
not  less  than  9  inches  in  thickness.    The  riprap  shall  be  laid  by  hand  and  the  base  of 
each  stone  shall  be  bedded  in  the  foundation  with  its  top  conforming  to  the  surface 
required.     All  spaces  between  the  stones  shall  be  filled  by  smaller  stones  and  gravel. 
The  thickness  of  the  riprap  shall  be  as  required  by  the  engineer,  and  the  thickness 
of  the  foundation  shall  be  not  less  than  two-thirds  the  required  thickness  of  the 
rock.     If  grouting  is  required  the  grout  shall  be  composed  of  i  part  cement  and  3 
parts  sand,  or  of  concrete  in  about  the  proportions  of  i  part  cement,  3  parts  sand 
and  6  parts  gravel  or  broken  stone,  which  shall  be  well  worked  in  between  the  rocks 
after  the  latter  are  laid. 

DRAINAGE 

56.  Description  and  Classification. — When  indicated  in  the  drawings  or  directed 
by  the  engineer,  drainage  conduits  shall  be  placed  to  lines  and  grades  as  required, 
and  due  precautions  shall  be  taken  to  maintain  the  same  in  perfect  condition  until 
the  completion  of  the  work.     Drains  shall  be  measured  and  estimated  by  the 
linear  foot. 

PLACING  METAL  WORK 

57.  Description. — The  gates,  frames  and  appurtenances,  steel  for  concrete  rein- 
forcement, the  cast-iron  lining  for  the  outlet  conduits,  and  all  other  metal  work, 
shall  be  set  as  shown  in  the  drawings  or  as  required  by  the  engineer.     Anchor  bolts 


546  SPECIFICATIONS 

shall  be  properly  built  into  the  concrete,  all  gates,  frames,  screens  and  operating 
devices  shall  be  set  in  correct  position  at  the  proper  time,  the  rising  stems  shall 
be  properly  alined,  and  the  whole  finally  left  in  good  working  order.  Embedded 
surfaces  shall  have  all  dirt  or  other  objectionable  material  removed  before  being 
placed  in  the  concrete.  Such  steel  bars  for  concrete  reinforcement  as  are  required 
by  the  drawings  or  by  direction  of  the  engineer  shall  be  accurately  placed  and  per- 
fect contact  shall  be  secured  between  the  bars  and  the  mortar  of  the  surrounding 
concrete.  Bars  shall  be  tightly  wired  together  at  all  points  of  intersection  and  so 
secured  in  position  that  they  will  not  be  disturbed  during  the  placing  of  the  con- 
crete. All  of  the  above-mentioned  metal  work,  except  steel  for  concrete  reinforce- 
ment, shall  be  purchased  through  the  chief  electrical  engineer. 

58.  Measurement.' — Placing  metal  work  shall  be  measured  and  estimated  as 
the  number  of  pounds  of  metal  work  in  place. 

59.  Pair.ting. — All  exposed  metal  work  after  erection  shall  be  thoroughly  cleaned 
and  finished  with  two  coats  oi  paint.     The  paint  shall  be  of  good  quality  graphite, 
or  other  material,  as  selected  by  the  engineer.     The  cost  of  painting  shall  be 
included  in  the  cost  of  placing  metal  work. 

OUTLET  CONDUITS 

60.  Description  and  Measurement. — The  dam  will  contain  25  or  more  outlet 
conduits  having  a  diameter  of  5  feet  throughout  the  greater  part  of  their  length. 
The  outlet  conduits  will  be  measured  and  estimated  by  the  linear  foot,  the  length 
of  a  given  conduit  being  considered  as  the  length  measured  on  the  center  line  of 
that  conduit.     All  cost  of  constructing  the  outlet  conduits  shall  be  charged  to 
"  outlet  conduits  "  except  the  cost  of  setting  the  cast  iron  linings,  anchor  bolts, 
etc.,  which  will  be  charged  to  "  placing  metal  work." 

INSPECTION  GALLERY 

61.  Description  and  Measurement. — An  inspection  gallery  of  varying  size  and 
elevation  shall  be  constructed  in  the  body  of  the  dam  as  shown  in  the  drawings 
or  as  directed  by  the  chief  engineer. 

The  inspection  gallery  shall  be  measured  and  estimated  by  the  linear  foot, 
the  length  being  considered  as  the  actual  length  of  the  center  line  of  the  gallery 
measured  along  planes  parallel  to  the  general  bottom  surface  of  the  gallery. 

LOG  HOIST 

62.  Description  and  Classification. — When  log  driving  in  the  Boise  River  is 
resumed  and  it  becomes  necessary  for  log  drives  to  pass  the  dam,  suitable  means 
shall  be  provided  for  hoisting  the  logs  from  the  reservoir  and  transporting  them  to 
the  river  below  the  dam.     All  expense  incurred  in  connection  with  such  hoisting 
and  transportation  shall  be  considered  a  single  item  and  classed  as  "  log  hoist 
and  chute." 


CONTRACT  SPECIFICATIONS  547 

CONTRACT  SPECIFICATIONS 
GENERAL  REQUIREMENTS 

1.  Form  of  Proposal  and  Signature. — -The  proposal  shall  be  made  on  the  form 
provided  therefor  and  shall  be  enclosed  in  a  sealed  envelope  marked  and  addressed 
as  required  in  the  notice  to  bidders.     The  bidder  shall  state  in  words  and  figures 
the  unit  prices  or  the  specific  sums,  as  the  case  may  be,  for  which  he  proposes  to 
supply  the  material  or  machinery  and  perform  the  work  required  by  these  speci- 
fications.    If  the  proposal  is  made  by  an  individual  it  shall  be  signed  with  his 
full  name,  and  his  address  shall  be  given;  if  it  is  made  by  a  firm  it  shall  be  signed 
with  the  copartnership  name  by  a  member  of  the  firm,  who  shall  also  sign  his  own 
name,  and  the  name  and  address  of  each  member  shall  be  given;  and  if  it  is  made 
by  a  corporation  it  shall  be  signed  by  an  officer  with  the  corporate  name  attested 
by  the  corporate  seal,  and  the  names  and  titles  of  all  officers  of  the  corporation 
shall  be  given. 

2.  Proposal.- — Blank  spaces  in  the  proposal  should  be  properly  filled.     The 
phraseology  of  the  proposal  must   not   be    changed,    and   no   additions   should 
be  made  to  the  items  mentioned  therein.     Unauthorized  conditions,  limitations 
or  provisos  attached  to  a  proposal  will  render  it  informal  and  may  cause  its  rejec- 
tion.    Alterations  by  erasure  or  interlineation  must  be  explained  or  noted  in  the 
proposal  over  the  signature  of  the  bidder.     If  the  unit  price  and  the  total  amount 
named  by  a  bidder  for  any  item  do  not  agree,  the  unit  price  alone  will  be  con- 
sidered  as  representing   the    bidder's    intention.     A   bidder   may   withdraw  his 
proposal  before  the  expiration  of  the  time  during  which  proposals  may  be  sub- 
mitted, without  prejudice  to  himself,  by  submitting  a  written  request  for  its  with- 
drawal to  the  officer  who  holds  it.     No  proposals  received  after  said  time  or  at 
any  place  other  than  the  place  of  opening  as  stated  in  the  advertisement  will  be 
considered.     Bidders,  their  representatives,  and  others  interested,  are  invited  to 
be  present  at  the  opening  of  proposals.     The  right  is  reserved  to  reject  any  or  all 
proposals,  to  accept  one  part  of  a  proposal  and  reject  the  other,  and  to  waive  tech- 
nical defects. 

3.  Certified  Check. — Each  bidder  shall  submit  with  his  proposal  an  uncondi- 
tional certified  check  for  the  sum  stated  in  the  notice  to  bidders,  payable  to  the 

order  of Any  condition  or  limitation  placed  upon  a  certified 

check  will  render  it  informal  and  may  result  in  the  rejection  of  the  proposal  under 
which  such  check  is  submitted.     If  the  bidder  to  whom  an  award  is  made  fails  or 
refuses  to  execute  the  required  contract  and  bond  within  the  time  specified  in  para- 
graph 4,  or  such  additional  time  as  may  be  allowed  by  the  engineer,  the  proceeds 
of  his  check  shall  become  subject  to  forfeit,  and  the  proceeds  of  said  check  are 
hereby  agreed  upon  as  liquidated  damages  on  account  of  the  delay  in  the  execution 
of  the  contract  and  bond  and  the  performance  of  work  thereunder,  and  the  neces- 
sity of  accepting  a  higher  or  less  desirable  bid  resulting  from  such  failure  or  refusal 
to  execute  contract  and  bond  as  required.     The  proceeds  of  the  check  of  the  suc- 
cessful bidder  will  be  returned  after  the  execution  of  his  contract  and  the  approval 
of  his  bond,  and  the  proceeds  of  the  checks  of  the  other  bidders  will  be  returned 
at  the  expiration  of  forty-five  days  from  the  date  of  opening  proposals,  or  sooner 
if  contract  is  executed  prior  to  that  time. 


548  SPECIFICATIONS 

4.  The  Contract. — The  bidder  to  whom  award  is  made  shall  execute  a  written 

contract  with and,  if  bond  is  required,  furnish  good  and  approved 

bond  within  fifteen  days  after  receiving  the  forms  of  contract  and  bond  for  execu- 
tion.    If  the  bidder  to  whom  award  is  made  fails  to  enter  into  contract  as  herein 
provided,  the  award  will  be  annulled,  and  an  award  may  be  made  to  the  bidder 
whose  proposal  is  next  most  acceptable  in  the  opinion  of  the  officer  by  whom 
the  first  award  was  made;  and  such  bidder  shall  fulfill  every  stipulation  embraced 
herein  as  if  he  were  the  party  to  whom  the  first  award  was  made.    The  adver- 
tisement, notice  to  bidders,  proposal,  general  conditions,  and  detail  specifications 
will  be  incorporated  in  the  contract.     A  corporation  to  which  an  award  is  made 
will  be  required,  before  the  contract  is  finally  executed,  to  furnish  evidence  of  its 
corporate  existence  and  evidence  that  the  officer  signing  the  contract  and  bond 
for  the  corporation  is  duly  authorized  to  so  do. 

5.  Contractor's  Bond. — Unless  another  sum  is  specified  in  the  notice  to  bidders, 
the  contractor  shall  furnish  bond  in  an  amount  not  less  than  20  per  cent  of  the 
estimated  aggregate  payments  to  be  made  under  the  contract,  conditioned  upon 
the  faithful  performance  by  the  contractor  of  all  covenants  and  stipulations  in 
the  contract.     Bonds  in  amounts  less  than  $5000  will  be  made  only  in  multiples 
of  $100;    in  amounts  exceeding  $5000  in  multiples  of  $1000;    provided  that  the 
amount  of  the  bond  shall  be  fixed  at  the  lowest  sum  that  will  fulfill  all  conditions 
herein  set  forth.     If  during  the  continuance  of  the  contract  any  of  the  sureties 

die   or   become   irresponsible,    may    require    additional   sufficient 

sureties,  which  the  contractor  shall  furnish  to  the  satisfaction  of  that  officer  within 
ten  days  after  notice,  and  in  default  thereof  the  contract  may  be  suspended  by 

and  the  materials  purchased  or  the  work  completed  as  provided  in 

paragraph  10. 

6.  Engineer. — The  word  "  engineer  "  used  in  these  specifications  or  in  the  con- 
tract means  the  Chief  Engineer  of He  will  be  represented  by  assist- 
ants and  inspectors,  authorized  to  act  for  him.      On  all  questions  concerning  the 
acceptability  of  material  or  machinery,  the  classification  of  material,  the  execution 
of  the  work,  conflicting  interests  of  contractors  performing  related  work;   and  the 
determination  of  costs,  the  decision  of  the  Chief  Engineer  shall  be  final,  and  binding 
upon  both  parties. 

7.  Contractor. — The  word  "  contractor  "  used  in  these  specifications  or  in  the 
contract  means  the  person,  firm,  or  corporation  with  whom  the  contract  is  made. 
The  contractor  shall  at  all  times  be  represented  on  the  works  in  person  or  by  a  fore- 
man or  duly  designated  agent.     Instructions  and  information  given  by  the  engi- 
neer to  the  contractor's  foreman  or  agent  on  the  work  shall  be  considered  as  having 
been  given  to  the  contractor.     When  two  or  more  contractors  are  engaged  on  in- 
stallation or  construction  work  in  the  same  vicinity  the  engineer  shall  be  authorized 
to  direct  the  manner  in  which  each  shall  conduct  his  work  so  far  as  its  affects  other 
contractors. 

8.  Material  and  Workmanship. — The  contractor  shall  submit  samples  or  speci- 
mens of  such  materials  to  be  furnished  or  used  in  the  work  as  the  engineer  may 
require.     All  materials  must  be  of  the  specified  quality  and  equal  to  approved 
samples  if  samples  have  been  submitted.     All  work  shall  be  done  and  completed 
in  a  thorough,   workmanlike    manner.     Work,  material,    or    machinery   not    in 
accordance  with    these   specifications,  in  the  opinion   of   the  engineer,  shall   be 


CONTRACT  SPECIFICATIONS  549 

made  to  conform  thereto.  Unsatisfactory  material  will  be  rejected,  and,  if  so 
ordered  by  the  engineer,  shall,  at  the  contractor's  expense,  be  immediately  re- 
moved from  the  vicinity  of  the  work. 

9.  Delays. — If  any  delay  is  caused  the  contractor  by  specific  orders  of  the  engi- 
neer to  stop  work,  or  by  the  performance  of  extra  work  ordered  by  the  engineer, 

or  by  the  failure  of to  provide  material,  or  necessary  instructions 

for  carrying  on  the  work,  or  to  provide  the  necessary  right  of  way,  or  site  for  instal- 
lation, or  by  unforeseen  causes  beyond  the  control  of  the  contractor,  such  delay 
will  entitle  the  contractor  to  an  equivalent  extension  of  time,  except  as  otherwise 
provided  in  paragraph  27.     Application  for  extension  of  time  must  be  approved 
by  the  engineer  and  shall  be  accompanied  by  the  formal  consent  of  the  sureties, 
but  an  extension  of  time,  whether  with  or  without  such  consent,  shall  not  release 
the  sureties  from  their  obligations,  which  shall  remain  in  full  force  until  the  dis- 
charge of  the  contract.     If  delays  from  any  of  the  above-mentioned  causes  occur 
after  the  expiration  of  the  contract  period  no  liquidated  damages  shall  accrue  for 
a  period  equivalent  to  such  delay. 

10.  Suspension  of  Contract. — If  the  contractor  fails  to  begin  the  delivery  of 
the  material  or  to  commence  work  as  provided  in  the  contract,  or  fails  to  make 
delivery  of  material  promptly  as  ordered,  or  to  maintain  the  rate  of  delivery  of 
material  or  progress  of  the  work  in  such  a  manner  as  in  the  opinion  of  the  engineer 
will  insure  a  full  compliance  with  the  contract  within  the  time  limit,  or  if  in  the 
opinion  of  the  engineer  the  contractor  is  not  carrying  out.  the  provisions  of  the  con- 
tract in  their  true  intent  and  meaning,  written  notice  will  be  served  on  him  to  pro- 
vide within  a  specified  time  for  a  satisfactory  compliance  with  the  contract,  and 
if  he  neglects  or  refuses  to  comply  with  such  notice  the  engineer  may  suspend  the 
operation  of  all  or  any  part  of  the  contract,  or  he  may  in  his  discretion  after  such 
notice  perform  any  part  of  the  work  or  purchase  any  or  all  of  the  material  included 
in  the  contract  or  required  for  the  completion  thereof  without  suspending  the 
contract.     Upon  suspension  of  contract,  the  engineer  may  in  his  discretion  take 
possession  of  all  or  any  part  of  the  machinery,  tools,  appliances,  animals,  materials, 
and  supplies  used  on  the  Work  covered  by  the  contract  or  that  have  been  delivered 
by  or  on  account  of  the  contractor  for  use  in  connection  therewith,  and  the  same 

may  be  used  either  directly  by or  by  other  parties  for  it, 

in  the  completion  of  the  work  suspended;    or may  employ 

other    parties    to  perform   the   work,   or   may   substitute   other    machinery    or 
materials,  purchase  the  material  contracted  for  in  such  manner  as  it  may  deem 
proper,  or  hire  such  force  and  buy  such  machinery,  tools,  appliances,  animals, 
materials,  and  supplies  at  the  contractor's  expense  as  may  be  necessary  for  the 

proper  conduct  and  completion  of  the  work.     Any  cost  to in  excess 

of  the  contract  price,  arising  from  the  suspension  of  the  contract,  or  from  work 

performed  or  purchases  made  by either  before  or  after  suspension, 

and  required  on  account  of  failure  of  the  contractor  to  comply  with  his  contract 
or  the  orders  of  the  engineer  issued  in  pursuance  thereof,  will  be  charged  to  the 
contractor  and  his  sureties,  who  shall  be  liable  therefor.     A  special  lien  to  secure 

the  claims  of in  the  event  of  suspension  of  the  contract  is  hereby 

created  against  any  property  of  the  contractor  taken  into  the  possession  of 

under  the  terms  hereof,  and  such  lien  may  be  enforced  by  a  sale  of  such  property, 
and  the  proceeds  of  the  sale,  after  deducting  all  expenses  thereof  and  connected 


550  SPECIFICATIONS 

therewith,  shall  be  credited  to  the  contractor.     If  the  net  credits  shall  be  in  excess 

of  the  claims  of against  the  contractor  the  balance  will  be  paid  to 

the  contractor  or  his  legal  representatives.  In  the  determination  of  the  question 
whether  there  has  been  such  noncompliance  with  the  contract  as  to  warrant  its 

suspension  or  the  furnishing  of  material  or  the  performance  of  work  by 

as  herein  provided,  the  decision  of  the  engineer  shall  be  final  and  binding  upon 
both  parties.  Suspension  of  the  contract,  or  any  part  thereof,  shall  operate  only 
to  terminate  the  right  of  the  contract  or  to  proceed  with  the  work  covered  by  the 
contract  or  the  suspended  portions  thereof.  The  provisions  of  the  contract  per- 
mitting   to  make  changes  and  to  make  proper  adjustment  of  accounts 

to  cover  any  increase  or  decrease  of  cost  on  account  of  such  changes,  and  all  other 
stipulations  of  the  contract  except  those  giving  the  contractor  the  right  to  proceed 
with  work  on  the  items  covered  by  the  suspension,  shall  be  and  remain  in  full 
force  and  effect  after  such  suspension  and  until  the  contract  shall  have  been  com- 
pleted and  final  payment  or  final  adjustment  of  accounts  made. 

11.  Changes. — The  engineer  may,  without  notice  to  the  sureties  on  the  contrac- 
tor's bond,  make  changes:    (a)  in  the  designs  or  materials  of  machinery;    (b)  in 
the  plans  for  installation  or  construction;    (c)  in  the  quantities  or  character  of  the 
work  or  material  required.     The  changes  in  plans  for  installation  or  construction 
may  also  include:    (a)  modifications  of  shapes  and  dimensions  of  canals,  dams, 
and  other  structures;    (b)  the  shifting  of  locations  to  suit  conditions  disclosed  as 
work  progresses.     If  such  changes  result  in  an  increase  of  cost  to  the  contractor, 
the  engineer  will  make  such  additions  on  account  thereof  as  he  may  deem  reason- 
able and  proper,  and  his  action  thereon  shall  be  final.     Extra  work  or  material 
shall  be  charged  for  as  hereinafter  provided. 

12.  Extra  Work  or  Material. — In  connection  with  the  work  covered  by  this  con- 
tract, the  engineer  may  at  any  time  during  the  progress  of  the  work  order  work 
or  material  not  covered  by  the  specifications.     Such  work  or  material  will  be  classed 
as  extra  work  and  will  be  ordered  in  writing.     No  extra  work  or  material  will  be 
paid  for  unless  ordered  in  writing.     Extra  work  or  material  shall  be  charged  for  at 
actual  necessary  cost,  as  determined  by  the  engineer,  plus  15  per  cent  for  profit, 
superintendence,  and  general  expenses.     The  actual  necessary  cost  will  include  all 
expenditures  for  materials,  labor,  and  supplies  furnished  by  the  contractor,  but 
will  in  no  case  include  any  allowance  for  office  expenses,  general  superintendence, 
or  other  general  expenses.     At  the  end  of  each  month  the  contractor  shall  present 
in  writing  any  claims  for  extra  work  performed  during  that  month  and  extra  mate- 
rial delivered  during  that  month  and,  when  requested  by  the  engineer,  shall  fur- 
nish itemized  statements  of  the  cost  and  shall  permit  examination  of  accounts, 
bills,  and  vouchers  relating  thereto.     No  such  claim  will  be  allowed  which  is  not 
presented  to  the  engineer  in  writing  within  thirty  days  after  the  close  of  the  month, 
during  which  the  extra  work  or  material  covered  by  such  claim  is  alleged  to  have 
been  furnished,  and  any  such  claim  not  so  presented  will  be  deemed  to  have  been 
waived  by  the  contractor. 

13.  Delays — No  Extra  Compensation. — The  contractor  shall  receive  no  com- 
pensation for  delays  or  hindrances  to  the  work  except  when,  in  the  judgment  of 
the  engineer,  direct  and  unavoidable  extra  cost  to  the  contractor  is  caused  by 

the  failure  of to  provide  necessary  information,  material,  right  of 

way,  or  site  for  installation.     When  such  extra  compensation  is  claimed  a  written 


CONTRACT  SPECIFICATIONS  551 

itemized  statement  setting  forth  in  detail  the  amount  thereof  shall  be  presented 
by  the  contractor  not  later  than  sixty  days  after  the  close  of  the  month  during 
which  extra  cost  is  claimed  to  have  been  incurred.  Unless  so  presented  the 
claim  shall  be  deemed  to  have  been  waived.  Any  such  claim,  if  found  correct, 
will  be  approved  and  the  amount  found  due  as  actual  extra  cost  will  be  covered 
by  the  next  estimate  thereafter  paid  under  the  contract.  The  decision  of  the 
engineer  whether  extra  cost  has  been  incurred  and  the  amount  thereof  shall  be 
final. 

14.  Changes  at  Contractor's  Request. — If  the  contractor,  on  account  of  conditions 
developing  during  the  progress  of  the  work,  finds  it  impracticable  to  comply  strictly 
with  these  specifications  and  applies  in  writing  for  a  modification  of  requirements 
or  of  methods  of  work,  such  change  may  be  authorized  by  the  engineer  if  not 
detrimental  to  the  work  and  if  without  additional  cost  to 

15.  Inspection. — All  materials  furnished  and  work  done  under  this  contract 
will  be  subject  to  rigid  inspection.     The  contractor  shall  furnish   without  extra 
charge  complete  facilities,  including  the  necessary  labor  for  the  inspection  of  all 
material  and  workmanship.     The  engineer,  or  his  authorized  agent,  shall  have 
at  all  times  access  to  all  parts  of  the  shop  where  such  material  under  his  inspection 
is  being  manufactured.     Work  or  material  that  does  not  conform  to  the  specifica- 
tions, although  accepted  through  oversight  or  otherwise,  may  be  rejected  at  any 
stage  of  the  work.     Whenever  the  contractor  on  installation  or  construction  is 
permitted  or  directed  to  do  night  work  or  to  vary  the  period  during  which  work  is 
carried  on  each  day,  he  shall  give  the  engineer  due  notice,  so  that  inspection  may 
be  provided.     Such  work  shall  be  done  without  extra  compensation  and  under 
regulations  to  be  furnished  in  writing  by  the  engineer. 

16.  Contractor's  Financial  Obligations. — The  contractor  shall  promptly  make 
payments  to  all  persons  supplying  labor  and  materials  in  the    execution  of  the 
contract,  and  a  condition  to  this  effect  shall  be  incorporated  in  the  contractor's 
bond. 

17.  Experience. — Bidders,  if  required,  shall  present  satisfactory  evidence  that 
they  have  been  regularly  engaged  in  furnishing  such  material  and  machinery  and 
constructing  such  work  as  they  propose  to  furnish  or  construct  and  that  they  are 
fully  prepared  with  necessary  capital,  machinery,  and  material  to  begin  the  work 
promptly  and  to  conduct  it  as  required  by  these  specifications. 

1 8.  Specifications  and  Drawings. — The  contractor  shall  keep  on  the  work  a 
copy  of  the  specifications  and  drawings  and  shall  at  all  times  give  the  engineer 
access  thereto.     Any  drawings  or  plans  listed  in  the  detail  specifications  shall 
be  regarded  as  part  thereof  and  of  the  contract.     Anything  mentioned  in  these 
specifications  and  not  shown  on  the  drawings  or  shown  on  the  drawings  and  not 
mentioned  in  these  specifications  shall  be  of  like  effect  as  though  shown  or  men- 
tioned in  both.     The  engineer  will  furnish  from  time  to  time  such  detail  drawings, 
plans,  profiles,  and  information  as  he  may  consider  necessary  for  the  contractor's 
guidance,  unless  otherwise  provided  in  the  proposal,  agreement,  or  detail  specifica- 
tions. 

19.  Local  Conditions. — Bidders  shall  satisfy  themselve  as  to  local  conditions 
affecting  the  work,  and  no  information  derived  from  the  maps,  plans,  specifica- 
tions, profiles,  or  drawings,  or  from  the  engineer  or  his  assistants,  will  relieve  the 
contractor  from  any  risk  or  from  fulfilling  all  of  the  terms  of  his  contract.     The 


552  SPECIFICATIONS 

accuracy  of  the  interpretation  of  the  facts  disclosed  by  borings  or  other  preliminary 
investigations  is  not  guaranteed.  Each  bidder  or  his  representative  should  visit 
the  site  of  the  work  and  familiarize  himself  with  local  conditions;  failure  to  do  so 
when  intelligent  preparation  of  bids  depends  on  a  knowledge  of  local  conditions 
may  be  considered  sufficient  cause  for  rejecting  a  proposal. 

20.  Data  to  be  Furnished  by  the  Contractor. — The  contractor  shall  furnish  the 
engineer  reasonable  facilities  for  obtaining  such  information  as  he  may  desire 
respecting  the  character  of  the  materials  and  the  progress  and  manner  of  the 
work,  including  all  information  necessary  to  determine  its  cost,  such  as  the  number 
of  men  employed,  their  pay,  the  time  during  which  they  worked  on  the  various 
classes  of  construction,  etc.     The  contractor  shall  also  furnish  the  engineer  copies 
of  freight  bills  on  all  machinery,  materials,  and  supplies  shipped  to  or  from  the 
project  in  connection  with  the  work  under  the  contract. 

21.  Restrictions  on  Disposition  of  Plant,  etc. — The  contractor  shall  not  make 
any  disposition  of  the  plant,  machinery,  tools,  appliances,  supplies,  materials,  or 
animals  used  on  or  in  connection  with  the  work,  either  by  sale,  conveyance,  or 
incumbrance,  inconsistent  with  the  special  lien  created  by  this  contract. 

22.  Damages. — The  contractor  will  be  held  responsible  for  and  required  to  make 
good,  at  his  own  expense,  all  damage  to  person  or  property  caused  by  carelessness 
or  neglect  on  the  part  of  the  contractor,  or  subcontractor,  or  the  agents  or  employees 
of  either. 

23.  Character  of  Workmen. — The  contractor  shall  not  allow  his  agents  or  employ- 
ees, his  subcontractors,  or  any  agent  or  employee  thereof,  to  trespass  on  premises 
or  lands  in  the  vicinity  of  the  work.     None  but  skilled  foremen  and  workmen  shall 
be  employed  on  work  requiring  special  qualifications,  and  when  required  by  the 
engineer  the  contractor  shall  discharge  any  person  who  commits  trespass  or  is 
in  the  opinion  of  the  engineer  disorderly,  dangerous,  insubordinate,  imcompetent, 
or  otherwise  objectionable.     Such  discharge  shall  not  be  the  basis  of  any  claim 
for  compensation  or  damages. 

24.  Methods  and  Appliances. — The  methods  and  appliances  adopted  by  the 
contractor  shall  be  such  as  will,  in  the  opinion  of  the  engineer,  secure  a  satisfactory 
quality  of  work  and  will  enable  the  contractor  to  complete  the  work  in  the  time 
agreed  upon.     If  at  any  time  the  methods  and  appliances  appear  inadequate,  the 
engineer  may  order  the  contractor  to  improve  their  character  or  efficiency,  and  the 
contractor  shall  conform  to  such  oroler;   but  failure  of  the  engineer  to  order  such 
improvement  of  methods  or  efficiency  will  not  relieve  the  contractor  from  his  obliga- 
tion to  perform  satisfactory  work  and  to  finish  it  in  the  time  agreed  upon. 

25.  Climatic  Conditions. — The  engineer  may  order  the  contractor  to  suspend 
any  work  that  may  be  subject  to  damage  by  climatic  conditions.     When  delay 
is  caused  by  an  order  to  suspend  work  given  on  account  of  climatic  conditions 
that  could  have  been  reasonably  foreseen  the  contractor  will  not  be  entitled  to  any 
extension  of  time  on  account  of  such  order. 

26.  Quantities  and  Unit  Prices. — The  quantities  noted  in  the  schedule  or  pro- 
posal are  approximations  for  comparing  bids,  and  no  claim  shall  be  made  for  excess 
or  deficiency  therein,  actual  or  relative.     Payment  at  the  prices  agreed  upon  will 
be  in  full  for  the  completed  work  and  will  cover  materials,  supplies,  labor,  tools, 
machinery,  and  all  other  expenditures  incident  to  satisfactory  compliance  with  the 
contract,  unless  otherwise  specifically  provided. 


CONTRACT  SPECIFICATIONS  553 

27.  Removal  and  Rebuilding  of  Defective  Work. — The  contractor  shall  remove 
and  rebuild  at  his  own  expense  any  part  of  the  work   that  has  been  improperly 
executed,  even  though  it  has  been  included  in  the  monthly  estimates.     If  he  refuses 
or  neglects  to  replace  such  defective  work,  it  may  be  replaced  at  the  expense  of 
the  contractor,  and  his  sureties  shall  be  liable  therefor. 

28.  Protection  of  Work  and  Cleaning  Up. — The  contractor  shall  be  responsible 
for  any  material  furnished  him  and  for  the  care  of  all  work  until  its  completion 
and  final  acceptance,  and  he  shall  at  his  own  expense  replace  damaged  or  lost 
material  and  repair  damaged  parts  of  the  work,  or  the  same  may  be  done  at  his 
expense,  and  his  sureties  shall  be  liable  therefor.     He  shall   take  all   risks  from 
floods  and  casualties  and  shall  make  no  charge  for  detention  from  such  causes. 
He  may,  however,  be  allowed  a  reasonable  extension  of  time  on  account  of  such 
detention,  subject  to  the  conditions  hereinbefore  specified.     The  contractor  shall 
remove  from  the  vicinity  of  the  completed  work  all  plant,  buildings,  rubbish, 
unused  material,  concrete  forms,  etc.,  belonging  to  him  or  used  under  his  direc- 
tion during  construction,  and  in  the  event  of  his  failure  to  do  so  the  same  may  be 
removed  at  the  expense  of  the  contractor,  and  his  sureties  shall  be  liable  therefor. 

29.  Roads  and  Fences. — Roads  subject  to  interference  from  the  work  covered 
by  this  contract  shall  be  kept  open,  and  the  fences  subject  to  interference  shall  be 
kept  up  by  the  contractor  until  the  work  is  finished. 

30.  Bench  Marks  and  Survey  Stakes. — Bench  marks  and  survey  stakes  shall  be 
established  by  the  engineer  and  shall  be  preserved  by  the  contractor,  and  in  case 
of  their  destruction  or  removal  by  him  or  his  employees,  they  will  be  replaced  by 
the  engineer  at  the  contractor's  expense,  and  his  sureties  shall  be  liable  therefor. 

31.  Right  of  Way. — The  site  for  the  installation  of  machinery  or  the  right  of 
way  for  the  works  to  be  constructed  under  this  contract  and  for  necessary  borrow 
pits,  channels,  spoil  banks,  ditches,  roads,  etc.,  will  be  provided  by 

32.  Sanitation. — The  engineer  may  establish  sanitary  and  police  rules  and  regu- 
lations for  all  forces  employed  under  this  contract,  and  if  the  contractor  fails  to 
enforce  these  rules  the  engineer  may  enforce  them  at  the  expense  of  the  contractor. 
The  use  or  sale  of  intoxicating  liquor  is  absolutely  prohibited  on  the  work,  except 
for  medicinal  purposes,  and  every  such  use  or  sale  shall  be  under  the  direction  and 
supervision  of  the  engineer. 

33.  Infringement  of  Patents. — The  contractor  shall  hold  and  save 

and  his  officers,  agents,  servants,  and  employees  harmless  from  and  against  all 
and  every  demand,  or  demands,  of  any  nature  or  kind,  for  or  on  account  of  the 
use  of  any  patented  invention,  article,  or  appliance  included  in  the  material  or 
supplies  hereby  agreed  to  be  furnished  under  this  contract,  and  should  the  contrac- 
tor, his  agents,  servants,  or  employees,  or  any  of  them,  be  enjoined  from  furnishing 
or  using  any  invention,  article,  material,  or  appliance  supplied  or  required  to  be 
supplied  or  used  under  this  contract,  the  contractor  shall  promptly  substitute 
other  articles,  materials,  or  appliances  in  lieu  thereof,  of  equal  efficiency,  quality, 
finish,  suitability,  and  market  value,  and  satisfactory  in  all  respects  to  the  engineer. 
Or,  in  the  event  that  the  engineer  elects,  in  lieu  of  such  substitution,  to  have  sup- 
plied, and  to  retain  and  use,  any  such  invention,  article,  material,  or  appliance, 
as  may  by  this  contract  be  required  to  be  supplied,  in  that  event  the  contractor 
shall  pay  such  royalties  and  secure  such  valid  licenses  as  may  be  requisite  and 
necessary  to  enable his  officers,  agents,  servants,  and  employees,  or 


554  SPECIFICATIONS 

any  of  them,  to  use  such  invention,  article,  material,  or  appliance  without  being 
disturbed  or  in  any  way  interfered  with  by  any  proceeding  in  law  or  equity  on  ac- 
count thereof.  Should  the  contractor  neglect  or  refuse  promptly  to  make  the  sub- 
stitution hereinbefore  required,  or  to  pay  such  royalties  and  secure  such  licenses 
as  may  be  necessary  and  requisite  for  the  purpose  aforesaid,  then  in  that  event 

the  engineer  shall  have  the  right  to  make  substitution,  or may  pay 

such  royalties  and  secure  such  licenses,  and  charge  the  cost  thereof  against  any 

money  due  the  contractor  from or  recover  the  amount  thereof  from 

him  and  his  surety,  notwithstanding  final  payment  under  this  contract  may 
have  been  made.  The  provisions  of  this  paragraph  do  not  apply  to  articles 
which  the  contractor  is  required  to  manufacture  or  furnish  in  accordance  with 

detail  drawings  furnished  by and  included  in  this  contract.    They 

shall  apply,  however,  where  such  drawings  and  the  specifications  cover  only  the 
type  of  device  without  restriction  as  to  details. 

SPECIAL  REQUIREMENTS 

34.  The  Requirement. — It  is  required  that  there  be  constructed  and  completed 
in  accordance  with  these  specifications  and  the  drawings  hereinbelow  listed, 
(items)                 (feature)                 (project)                 (State).     The    work    is    near 
the  line  of  the Railway  and  in  the  vicinity  of  the  towns  of 

35.  List  of  Drawings. 


36.  Commencement,   Prosecution   and   Completion   of  Work. — Work    shall    be 

commenced  by  the  contractor  within days,  and  shall  be  completed  within 

days  after  the  execution  of  the  contract.     The  contractor  shall    at    all 

times  during  the  continuation  of  the  contract  prosecute  the  work  with  such  force 
and  equipment  as,  in  the  judgment  of  the  engineer,  are  sufficient  to  complete  it 
within  the  specified  time. 

37.  Failure  to  Complete  the  Work  in  the  Time  Agreed  upon. — Should  the  con- 
tractor fail  to  complete  the  work  or  any  part  thereof  in  the  time  agreed  upon  in 
the  contract,  or  in  such  extra  time  as  may  have  been  allowed  for  delays  by  formal 

extensions,  a  deduction  of dollars  per  day  for  each  schedule  will  be 

made  for  each  and  every  day,  including  Sundays  and  holidays,  that  such  schedule 
remains  uncompleted  after  the  date  required  for  the  completion.     The  said  amounts 

are  hereby  agreed  upon  as  liquidated  damages  for  the  loss  to on 

account  of  all  expenses  due  to  the  employment  of  engineers,  inspectors  and  other 
employees  after  the  expiration  of  the  time  for  completion  and  OH  account  of  the 
value  of  the  operation  of  the  works  dependent  thereon,  and  will  be  deducted  from 
any  money  due  the  contractor  under  this  contract,  and  the  contractor  and  his 
sureties  shall  be  liable  for  any  excess. 

38.  Progress   Estimates   and   Payments.— At  the  end  of  each  calendar  month 
the  engineer  will  make  an  approximate  measurement  of  all  work  done  and  material 
delivered  up  to  that  date,  classified  according  to  items  named  in   the  contract, 
and  will  make  an  estimate  of  the  value  of  the  same  on  the  basis  of  the  unit  prices 
named  in  the  contract.     To  the  estimate  made  as  above  set  forth  will  be  added 
the  amounts  earned  for  extra  work  to  the  date  of  the  progress  estimate.    From 


SPECIAL  REQUIREMENTS  555 

the  total  thus  computed  a  deduction  of  10  per  cent  will  be  made  and  from  the  re- 
mainder there  will  be  further  deducted  any  amount  due  to from  the 

contractor  for  supplies  or  materials  furnished  or  services  rendered  and  any  other 

amounts  that  may  be  due  to as  damages  for  delays  or  otherwise 

under  the  terms  of  the  contract.  From  the  balance  thus  determined  will  be  de- 
ducted the  amount  of  all  previous  payments  and  the  remainder  will  be  paid  to 
the  contractor  upon  the  approval  of  the  accounts.  The  10  per  cent  deducted 
as  above  set  forth  will  become  due  and  payable  with  and  as  a  part  of  the  final 
payment  to  be  made  as  hereinafter  provided.  In  case  of  the  suspension  of  the  con- 
tract, the  said  10  per  cent  shall  be  and  become  the  sole  and  absolute  property  of 

to  the  extent  necessary  to  repay any  excess  in  the  cost 

of  the  work  above  the  contract  price.  When  the  terms  of  the  contract  shall  have 
been  fully  complied  with  to  the  satisfaction  of  the  engineer,  final  payment  will  be 
made  of  any  balance  due,  including  the  percentage  withheld  as  above,  or  such 
portion  thereof  as  may  be  due  to  the  contractor. 

39.  Materials  Furnished  by  the  United  States. — All  (list  items) 

,  required  for  the  completion  of  the  work  in  accordance  with  these  speci- 
fications, will  be  furnished  to  the  contractor  by and  will  be  delivered 

to  him  f.  o.  b.  cars  at  the  railway  station  most  convenient  to  the  work.     The  con- 
tractor shall  haul  all  materials  from  the  points  of  delivery  to  the  work.     He  shall 
provide  suitable  warehouses  for  storing  materials  and  will  be  charged  for  any  mate- 
rial lost  or  damaged  after  delivery  to  him.     He  shall  return  to all 

unused  material  and  will  be  charged  for  any  material  not  used  and  not  returned 

the  same  amounts  that  the  material  cost at  the  point  of  delivery  to 

him.     When  material  is  furnished  to  the  contractor  on  cars  he  shall  be  responsible 
for  the  prompt  unloading  of  such  material  and  will  be  held  liable  for  any  demurrage 
charges  which  may  be  incurred  by  his  failure  to  unload  the  material  promptly. 
The  cost  of  unloading,  hauling,  handling,  storing  and  caring  for  materials  furnished 

by shall  be  included  in  the  unit  prices  bid  for  the  work  in  which  the 

materials  are  to  be  used. 

STANDARD  PARAGRAPHS  FOR  PURCHASE  OF  MATERIAL 

40.  Test  Pieces. — The  contractor  shall  provide,  at  his  own  expense,  the  neces- 
sary test  pieces,  and  shall  notify  the  engineer  or  his  representative  when  these  pieces 
are  ready  for  testing.     All  test  bars  and  test  pieces  shall  be  marked  so  as  to  indicate 
clearly  the  material  they  represent,  and  shall  be  properly  boxed  and  prepared  for 
shipment  if  required. 

41.  Tests. — Physical  tests  and  chemical  analyses  of  material  will  be  made  by 
at  his  own  expense;   or  they  may  be  made  at  the  plant  by  the  con- 
tractor or  his  employees,  acting  under  the  direction  of  the  engineer  or  his  repre- 
sentative;   or  certified  tests  may,  at  the  option  of  the  engineer,  be  accepted  in 
lieu  of  the  above-mentioned  tests. 

42.  Shipment. — All  shipments  shall  be   made  to  the  points  directed  by  the 
engineer. 

43.  Payment. — per  cent  of  the  contract  price  of  each  shipment  will  be 

paid  on  the  acceptance  of  the  material  by  the  inspector  and  receipt  by  the  engineer 

at of  the  bill  of  lading,  properly  receipted,  and  the  remainder  shall 

be  paid  when  all  of  the  material  covered  by  the  contract  shall  have  been  received 


556  SPECIFIC  A  TIONS 

at  its  destination  and  finally  inspected,  checked  and  accepted  by  the  engineer, 
and  the  terms  of  the  contract  shall  have  been  fully  complied  with  to  the  satis- 
faction of  the  engineer. 

EARTHWORK  ON  CANALS 

44.  Classification  of  Excavation. — All   materials   moved  in  the  excavation  of 
canals  and  for  structures,  and  in  the  construction  of  embankments  will  be  measured 
in  excavation  only,  to  the  neat  lines  shown  in  the  drawings  or  prescribed  by  the 
engineer,  and  will  be  classified  for  payment  as  follows: 

Class  i :  Material  that  can  be  plowed  to  a  depth  of  6  inches  or  more  with  a  six- 
horse  or  six-mule  team,  each  animal  weighing  not  less  than  1400  pounds,  attached 
to  a  suitable  plow,  all  well  handled  by  at  least  three  men;  also  all  material  that  is 
loose  and  can  be  handled  in  scrapers,  and  all  detached  masses  of  rock,  not  exceeding 
2  cubic  feet  in  volume,  occurring  in  loose  material  or  material  that  can  be  plowed 
as  specified. 

Class  2:  Indurated  material  of  all  kinds  that  cannot  be  plowed  as  described 
under  class  i  but  that,  when  loosened  by  powder  or  other  suitable  means,  can  be 
removed  by  the  use  of  plows  and  scrapers,  and  all  detached  masses  of  rock  more 
than  2  and  not  exceeding  10  cubic  feet  in  volume. 

Class  3:  All  rock  in  place  not  included  in  classes  i  and  2,  and  all  detached 
masses  of  rock  exceeding  10  cubic  feet  in  volume  not  included  in  classes  i  and  2. 

If  there  be  required  the  excavation  of  any  material  which,  in  the  opinion  of  the 
engineer,  cannot  properly  be  included  in  any  of  the  above  three  classes,  the  engineer 
will  determine  the  actual  necessary  cost  of  excavating  and  disposing  of  such  mate- 
rial and  payment  therefor  as  extra  work  will  be  made  under  the  provisions  of 
paragraph  ....  of  these  specifications.  No  additional  allowance  above,  the  prices 
bid  for  the  several  classes  of  material  will  be  made  on  account  of  any  of  the  material 
being  frozen.  It  is  desired  that  the  contractor  or  his  representative  be  present 
during  the  measurement  of  material  excavated.  On  written  request  of  the  con- 
tractor, made  by  him  within  ten  days  after  the  receipt  of  any  monthly  estimate,  a 
statement  of  the  quantities  and  classifications  between  successive  stations  in- 
cluded in  said  estimate  will  be  furnished  him  within  ten  days  after  the  receipt  of 
such  request.  This  statement  will  be  considered  as  satisfactory  to  the  contractor 
unless  he  files  with  the  engineer,  in  writing,  specific  objections  thereto,  with  reasons 
therefor,  within  ten  days  after  receipt  of  said  statement  by  the  contractor  or  his 
representative  on  the  work.  Failure  to  file  such  written  objection  with  reasons 
therefor  within  said  ten  days  shall  be  considered  a  waiver  of  all  claims  based  on 
alleged  erroneous  estimate  of  quantities  or  incorrect  classification  of  materials 
for  the  work  covered  by  such  statement. 

45.  Canal  Sections. — The  canal  sections  are  shown  in   the  drawings,  but  the 
undetermined  stability  of  the  material  that  will  form  the  canal  banks  may  make  it 
desirable  during  the  progress  of  the  work  to  vary  the  slopes  and  dimensions  depen- 
ent  thereon.     Increase  or  decrease  of  quantities  excavated  as  a  result  of  such 
changes  shall  be  covered  in  the  estimates  and  shall  not  otherwise  affect  the  payments 
due  to  contractor,  unless  it  is  found  by  the  engineer  that  the  unit  cost  is  thereby 
increased,  in  which  case  the  engineer  will  estimate,  and  include  in  the  amount  due 
the  contractor  the  amount  of  such  increase.     The  canal  shall  be  excavated  to  the 
full  depth  and  width  required  and  must  be  finished  to  the  prescribed  lines  and 


SPECIAL  REQUIREMENTS  557 

grades  in  a  workmanlike  manner.  Runways  shall  not  be  cut  into  canal  slopes 
below  the  proposed  water  level.  Earth  slopes  shall  be  neatly  finished  with  scrapers 
or  similar  appliances.  Rock  bottoms  and  banks  must  show  no  points  of  rock 
projecting  more  than  0.3  foot  into  the  prescribed  section.  Above  the  water  line 
the  rock  will  be  allowed  to  stand  at  its  steepest  safe  angle  and  no  finishing  will  be 
required  other  than  the  removal  of  rock  masses  that  are  liable  to  fall.  Payment 
for  excavation  of  canals  will  be  made  to  the  neat  lines  only  as  shown  in  the  drawings 
or  as  established  by  the  engineer. 

46.  Preparation  of  Surfaces. — The  ground  under  all  embankments  that  are  to 
sustain  water  pressure,  and  the  surface  of  all  excavation  that  is  to  be  used  for  em- 
bankments, shall  be  cleared  of  trees,  brush  and  vegetable  matter  of  every  kind. 
The  roots  shall  be  grubbed  and  burned  with  other  combustible  material  that 
has  been  removed.     The  surface  of  the  ground  under  the  entire  embankment  shall 
be  scored  with  a  plow  making  open  furrows  not  less  than  8  inches  deep  below  the 
natural  ground  surface  at  intervals  of.  not  more  than  3  feet.     The  cost  of  all  work 
described  in  this  paragraph  shall  be  included  in  the  unit-prices  bid  for  excavation. 

47.  Construction     of    Embankments. — Embankments    built    with    teams    and 
scrapers  or  with  dump  wagons  shall  be  made  in  layers  not  exceeding  12  inches  in 
thickness  and  kept  as  level  as  practicable.     The  travel  over  the  embankments 
during  construction  shall  be  so  directed  as  to  distribute  the  compacting  effect  to 
the  best  advantage.     Any  additional  compacting  required  over  that  produced  by 
ordinary  travel  in  distributing  the  material  will  be  ordered  in  writing  and  paid 

for  as  extra  work  under  the  provisions  of  paragraph Embankments  shall 

be  built  to  the  height  designated  by  the  engineer  to  allow  for  settlement,  and  shall 
be  leveled  on  top  to  a  regular  grade.     (Note:    If  the  engineer  proposes  to  permit 
the  use  of  machinery  in  canal  excavation  full  specifications  should  be  drafted  in  each 
individual  case.)     No  embankments  shall  be  made  from  frozen  materials  nor  on 
frozen  surfaces.     Should  the  engineer  direct  that  unsuitable  material  be  excavated 
and  removed  from  the  site  of  any  embankment,  the  material  thus  excavated  will 
be  paid  for  as  excavation.     When  canal  excavation  precedes  the  building  of  struc- 
tures, openings  shall  be  left  in  the  embankments  at  the  sites  of  these  structures 
and,  except  when  the  construction  of  the  structures  is  included  in  the  contract, 
the  contractor  will  not  be  required  to  complete  such  omitted  embankments.     The 
cost  of  all  work  described  in  this  paragraph,  except  as  herein  specified,  shall  be  in- 
cluded in  the  prices  bid  for  excavation. 

48.  Disposal  of  Materials. — -All  suitable  material  excavated   in    the  construc- 
tion of  canals  and  structures,  or  so  much  thereof  as  may  be  needed,  shall  be  used 
in  the  construction  of  embankments  and  in  backfilling  around  structures.     Where 
the  canal  is  on  sloping  ground,  all  material  taken  from  the  excavation  shall  be 
deposited  on  the  lower  side  of  the  canal  unless  otherwise  shown  in  the  drawings  or 
directed  by  the  engineer.     Where  the  canal  is  on  level  or  nearly  level  ground,  the 
material  from  the  excavation  shall  be  deposited  in  embankments  on  both  sides  to 
form  the  top  portions  of  the  waterway.     If  there  is  an  excess  of  material  in  excava- 
tion it  shall  be  used  to  strengthen  the  embankment  on  either  side  of  the  canal  as 
may  be  directed  by  the  engineer.     Material  taken  from  cuts  that  is  not  suitable 
for  embankment  construction  and  surplus  material  may  be  wasted  on  the  right  of 
way  owned  by ,  at  such  points  as  shall  be  approved  by  the  engi- 
neer.    Unless  otherwise  shown  in  the  drawings  or  directed  by  the  engineer,  no 


558  SPECIFICATIONS 

material  shall  be  wasted  in  drainage  channels,  nor  within feet  of  the  edge 

of  the  prescribed  or  actual  canal  cut.  On  side  hill  locations  all  material  wasted 
shall  be  placed  on  the  lower  side  of  the  canal  unless  specific  written  authority  is 
obtained  from  the  engineer  to  waste  such  material  elsewhere.  Waste  banks  shall 
be  left  with  reasonably  even  and  regular  surfaces.  Whenever  directed  by  the 
engineer,  materials  found  in  the  excavation,  such  as  sand,  gravel  or  stone,  that  are 
suitable  for  use  in  structures,  or  that  are  otherwise  required  for  special  purposes, 
shall  be  preserved  and  laid  aside  in  some  convenient  place  designated  by  him. 

49.  Borrow  Pits. — Where  the  canal  excavation  at  any  section  does  not  furnish 
sufficient  suitable  material  for  embankments,  the  engineer  will  designate  where 
additional  material  shall  be  procured.     Unless  otherwise  shown  on  the  drawings 
or  directed  by  the  engineer  a  berm  of  10  feet  shall  be  left  between  the  outside  toe 
of  the  embankment  and  the  edge  of  the  borrow  pit,  with  provision  for  a  side  slope 
of  two  to  one  to  the  bottom  of  the  borrow  pit.     Borrowed  material  will  be  measured 
in  excavation  only,  and  unless  the  engineer  gives  the  contractor  specific  written 
orders  to  excavate  other  than  class  i  material  from  borrow  pits,  all  material  obtained 
from  this  source  will  be  paid  for  at  the  unit  price  bid  for  class  i  excavation,  regard- 
less of  its  actual  character.    Payment  for  excavation  from  borrow  pits  will  be  made 
for  only  such  quantities  as  are  required  for  embankments  or  backfilling  or  such  as 
by  direction  of  the  engineer  are  excavated  and  wasted  or  laid  aside. 

50.  Overhaul. — All  material  taken  from  the  excavation  and  required  for  em- 
bankment or  for  other  purposes  shall  be  placed  as  directed  by  the  engineer.     The 
limit  of  free  haul  will  be  200  feet.     Necessary  haul  over  200  feet  will  be  paid  for 
at  the  price  bid  per  cubic  yard  per  hundred  feet  additional  haul,  but  no  allowance 
will  be  made  for  overhaul  where  the  excavated  material  is  wasted,  except  where 
such  overhaul  is  specifically  ordered  in  wrriting  by  the  engineer.     Where  material 
is  taken  from  borrow  pits,  the  length  of  the  haul  will  be  measured  along  the  shortest 
practicable  route  between  the  center  of  gravity  of  the  material  as  found  in  excava- 
tion and  the  center  of  gravity  of  the  material  as  deposited  in  each  station.     Where 
the  material  is  taken  from  canal  excavation,  the  length  of  the  haul  shall  be  under- 
stood to  mean  the  distance  measured  along  the  center  line  of  the  canal  from   the 
center  of  gravity  of  the  material  as  found  in  excavation  to  the  center  of  gravity 
of  the  material  as  required  to  be  deposited. 

51.  Surface  and  Berm  Ditches. — If,  in  the  judgment  of  the  engineer,  it  should 
be  necessary  to  construct  surface  and  berm  drainage  ditches  along  the  lines  of  the 
canal,  the  contractor  shall  perform  such  work  and  the  excavation  will  be  paid  for 
at  the  unit  prices  bid  in  the  schedules  covering  the  excavation  of  the  canal  along 
which  such  surface  and  berm  ditches  are  built. 

52.  Excavation    for   Structures. — Unless     otherwise   shown    in    the   drawings, 

excavation  for  structures  will  be  measured  for  payment  to  lines outside 

of  the  foundation  of  the  structures  and  to  slopes  of  ;    provided, 

that,  where  the  character  of  the  material  cut  is  such  that  it  can  be  trimmed  to  the 
required  lines  of  the  concrete  structure  and  the  concrete  placed  against  the  sides 
of  the  excavation  without  the  use  of  intervening  forms,  payment  for  excavation 
will  not  be  made  outside  of  the  required  limits  of  the  concrete.     The  prices  bid  for 
excavation  shall  include  the  cost  of  all  labor  and  material  for  cofferdams  and  other 
temporary  structures  and  of  all  pumping,  bailing,  draining  and  all  other  work 
necessary  to  maintain  the  excavation  in  good  order  during  construction. 


SPECIAL  REQUIREMENTS  559 

53.  Backfilling. — The  contractor  shall  place  and   shall   compact   thoroughly 
all  backfilling  around  structures.     The  compacting  must  be  equivalent  to  that 
obtained  by  the  tramping  of  well  distributed  scraper  teams  depositing  the  mate- 
rial in  layers  not  exceeding  6  inches  thick  when  compacted.     The  material  used  for 
this  purpose,  the  amount  thereof  and  the  manner  of  depositing  the  same  must 
be  satisfactory  to  the  engineer.     So  far  as  practicable,  the  material  moved  in 
excavating  for  structures  shall  be  used  for  backfilling,  but  when  sufficient  suitable 
material  is  not  available  from  this  source,  additional  material  shall  be  obtained 
from  borrow  pits  selected  by  the  engineer.     Payment  for  backfilling  will  be  made 
at  the  price  per  cubic  yard  bid  therefor  in  the  schedule. 

54.  Puddling. — Backfilling  and  embankment  around  structures  within  .  . .  .feet 
of  the  structure  shall  be  made  with  material  approved  by  the  engineer,  and  where 
practicable  shall  consist  of  the  sand  and  gravel,  with  an  admixture  of  clay  equal 
to  one-fourth  to  one-half  the  volume  of  sand  and  gravel.     The  material  shall  be 
deposited  in  water  of  such  depth  as  is  approved  by  the  engineer,  unless  the  quantity 
of  clay  predominates,  in  which  case  the  engineer  may  in  his  discretion  order  the 
material  deposited  in  layers  of  6  inches  or  less,  and  compacted  by  tamping  or  roll- 
ing with  the  smallest  quantity  of  water  that  will  insure  consolidation.     Payment 
for  the  work  specified  in  this  paragraph  will  be  made  at  the  unit  price  bid  for  pud- 
dling and  will  be  in  addition  to  the  payment  made  for  excavation  and  overhaul. 

55.  Blasting. — Any  blasting  that  will  probably  injure  the  work  will  not  be 
permitted,  and  any  damage  done  to  the  work  by  blasting  shall  be  repaired  by  the 
contractor  at  his  expense. 

CONCRETE 

56.  Composition. — Concrete  shall  be  composed    of   cement,  sand  and  broken 
rock  or  clean  gravel,  well  mixed  and  brought  to  a  proper  consistency  by  the  addi- 
tion of  water.     Ordinarily  one  part  by  volume,  measured  loose,  of  cement  shall  be 

used  with parts  of  sand  and parts  of  broken  rock  or  gravel.     These 

proportions  may  be  modified  by  the  engineer  as  the  work  or  the  nature  of  the  mate- 
rials used  may  render  it  desirable,  and  the  contractor  shall  not  be  entitled  to  any 
extra  compensation  by  reason  of  such  modifications. 

57.  Cement. — Cement  for  the  concrete  will  be  furnished  to  the  contractor  by 
as  provided  in  paragraph The  contractor  shall  give  the  engi- 
neer not  less  than  thirty  days'  notice  in  writing  of  his  cement  requirements.     The 
requirements  shall  be  stated,  so  far  as  practicable,  in  quantities  not  less  than  single 

car  lots.     The  contractor  shall  return  to  the  railway  station  at ,  all 

empty  sacks  securely  bound  in  bundles  in  such  manner  and  of  such  sizes  as  the 
engineer  may  direct.    For  all  sacks  not  returned  in  serviceable  condition,  he  will  be 
charged  the  same  amount  that  the  sacks  cost. 

58.  Reinforcement  Bars. — Steel  bars  shall  be  placed  in  the  concrete  wherever 
shown  in  the  drawings  or  prescribed  by  the  engineer.     The  steel  will  be  furnished 

to  the  contractor  by as  provided  in  paragraph The  exact 

position  and  shape  of  reinforcement  bars  are  not  shown  in  all  cases  in  the  drawings 
accompanying  these  specifications,  but  the  contractor  will  be  furnished  supple- 
mental detailed  drawings  and  lists  which  will  give  him  the  information  necessary 
for  cutting,  bending  and  spacing  of  bars.     The  steel  used  for  concrete  reinforcement 
shall  be  so  secured  in  position  that  it  will  not  be  displaced  during  the  deposition 


560  SPECIFICATIONS 

of  the  concrete,  and  special  care  shall  be  exercised  to  prevent  any  disturbance  of 
the  steel  in  concrete  that  has  already  been  placed.  The  cost  of  hauling,  storing, 
cutting,  bending,  placing  and  securing  in  position  of  reinforcement  bars  shall 
be  included  in  the  unit  price  bid  for  placing  reinforcement  bars. 

59.  Sand. — Sand  for  concrete  may  be  obtained  from  natural  deposits  or  may 
be  made  by  crushing  suitable  rock.     The  sand  particles  shall  be  hard,  dense,  dur- 
able rock  fragments,  such  as  will  pass  a  |-inch  mesh  screen.     The  sand  must  be 
free  from  organic  matter  and  must  not  contain  more  than  10  per  cent  of  clayey 
material.     The  sand  must  be  so  graded  that  when  dry  and  well  shaken  its  voids 
will  not  exceed  35  per  cent. 

60.  Broken  Rock  or  Gravel. — The  broken  rock  or  gravel  for  concrete  must  be 

hard,  dense,  durable  rock  fragments  or  pebbles  that  will  pass  through  a 

inch  mesh  screen  when  used  for  plain  concrete,  and  through  a inch  mesh 

screen  when  used  for  reinforced  concrete,  and  that  will  be  rejected  by  a  jj-inch 
mesh  screen. 

61.  Water. — The  water  used  in  mixing  concrete  must  be  reasonably  clean  and 
free  from  objectionable  quantities  of  organic  matter,  alkali  salts  and  other  impuri- 
ties. 

62.  Mixing. — The  cement,  sand  and  broken  rock  or  gravel  shall  be  so  mixed 
and  the  quantities  of  water  added  shall  be  such  as  to  produce  a  homogeneous  mass 
of  uniform  consistency.     Dirt  and  other  foreign  substance  shall  be  carefully  ex- 
cluded.    Machine  mixing  will  be  required  unless  specific  authority  to  use  hand 
mixing  is  given  by  the  engineer.     The  machine  and  its  operation  shall  be  subject 
to  the  approval  of  the  engineer.     Hand  mixing,  if  permitted,  shall  be  thorough 
and  shall  be  done  on  a  clean,  tight  floor.     In  general,  enough  water  shall  be  used 
in  mixing  to  give  the  concrete  the  consistency  ordinarily  designated  as  "  wet." 
Concrete  containing  a  minimum  amount  of  water,  ordinarily  designated  as  "  dry  " 
concrete,  will  be  permitted  only  where  the  nature  of  the  work  renders  the  use  of 
"  wet  "  concrete  impracticable.     If   concrete  is  mixed   in   freezing   weather,  the 
materials  shall  be  heated  sufficiently  .before  mixing  to  remove  all  frost  and  main- 
tain a  temperature  above  32°  F.,  until  the  concrete  has  been  placed  in  the  work 
and  has  attained  its  final  set. 

63.  Placing. — Concrete  shall  be  placed  in  the  work  before  the  cement  takes  its 
initial  set.     The  cement  used  in  any  concrete  that  is  wasted  or  rejected  will  be 
charged  to  the  contractor  at  its  cost,  at  the  point  of  delivery  to  him.     No  con- 
crete shall  be  placed  in  water  except  by  permission  of  the  engineer  and  the  method 
of  depositing  the  same  shall  be  subject  to  his  approval.     Foundation  surfaces 
upon  which  concrete  is  to  be  placed  must  be  free  from  mud  and  debris.     When  the 
placing  of  concrete  is  to  be  interrupted  long  enough  for  the  concrete  to  take  its 
final  set,  the  working  face  shall  be  given  a  shape,  by  the  use  of  forms  or  other 
means,  at  the  option  of  the  engineer,  that  will  secure  proper  union  with  subsequent 
work.     All  concrete  surfaces  upon  or  against  which  concrete  is  to  be  placed  and  to 
which  the  new  concrete  is  to  adhere,  shall  be  roughened,  thoroughly  cleaned,  and 
wet  before  the  concrete  is  deposited.     "  Dry  "  concrete  shall  be  deposited  in  layers 
not  exceeding  6  inches  in  thickness,  each  of  which  shall  be  rammed  until  water 
appears  on  the  surface.     "  Wet  "  concrete  shall  be  stirred  with  suitable  tamping 
bars,  shovels  or  forked  tools  until  it  completely  fills  the  form,  closes  snugly  against 
all  surfaces  and  is  in  perfect  and  complete  contact  with  any  steel  used  for  rein- 


SPECIAL  REQUIREMENTS  561 

forcement.  Where  smooth  surfaces  are  required  a  suitable  tool  shall  be  worked 
up  and  down  next  to  the  form  until  the  coarser  material  is  forced  back  and  a  mortar 
layer  is  brought  next  to  the  form.  No  concrete  shall  be  placed  except  in  the  pres- 
ence of  a  duly  authorized  inspector. 

64.  Finishing. — The  surface  of  concrete  finished  against  forms  must  be  smooth, 
free  from  projections  and  thoroughly  filled  with  mortar.     Immediately  upon  the 
removal  of  forms  all  voids  shall  be  neatly  filled  with  cement  mortar,  irregularities 
in  exposed  surfaces  shall  be  removed  and  minor  imperfections  of  finish  shall  be 
smoothed  to  the  satisfaction  of  the  engineer.     Exposed  surfaces  of  concrete  not 
finished  against  forms,  such  as  horizontal  or  sloping  surfaces,  shall  be  brought  to  a 
uniform  surface  and  worked  with  suitable  tools  to  a  smooth  mortar  finish.     All 
sharp  angles  where  required  shall  be  rounded  or  beveled  by  the  use  of  moulding 
strips  or  suitable  moulding  or  finishing  tools. 

65.  Protection. — The   contractor    shall   protect   all   concrete   against    injury. 
Exposed  surfaces  of  concrete  shall  be  protected  from  the  direct  rays  of  the  sun  and 
shall  be  kept  damp  for  at  least  two  weeks  after  the  concrete  has  been  placed. 
Concrete  laid  in  cold  weather  shall  be  protected  from  freezing  by  such  means 
as  are  approved  by  the  engineer.     All  damage  to  concrete  shall  be  repaired  by  the 
contractor  at  his  expense,  in  a  manner  satisfactory  to  the  engineer. 

66.  Forms. — Forms  to  confine  the  concrete  and  shape  it  to  the  required  lines 
shall  be  used  wherever  necessary.     Where  the  character  of  the  material  cut  into 
to  receive  a  concrete  structure  is  such  that  it  can  be  trimmed  to  the  prescribed 
lines,  the  use  of  forms  will  not  be  required.     The  forms  shall  be  of  sufficient  strength 
and  rigidity  to  hold  the  concrete  and  to  withstand  the  necessary  pressure  and  ram- 
ming without  deflection  from  the  prescribed  lines.     For  concrete  surfaces  that  will 
be  exposed  to  view  and  for  all  other  concrete  surfaces  that  are  to  be  finished  smooth, 
the  lagging  of  forms  must  be  surfaced  and  bevel-edged  or  matched;  provided,  that 
smooth  metal  forms  may  be  used  if  desired.     All  forms  shall  be  removed  by  the 
contractor,  but  not  until  the  engineer  gives  permission.     Forms  may  be  used 
repeatedly  provided  they  are  maintained  in  serviceable  condition  and  thoroughly 
cleaned  before  being  re-used. 

67.  Measurement. — Concrete  will  be  measured   for  payment  to  the  neat  lines 
shown  in  the  drawings  or  prescribed  by  the  engineer  under  these  specifications. 
No  payments  will  be  made  for  concrete  outside  of  the  prescribed  lines  and  in  case 
cavities  resulting  from  careless  excavation  are  required  to  be  filled  with  concrete, 
the  cement  used  for  such  refilling  will  be  charged  to  the  contractor  at  its  cost  at 
the  point  of  delivery  to -him. 

68.  Payment. — The  unit  price  bid  for  concrete  shall  include  all  material  and 
labor  entering  into  its  construction,  except  that  cement  will  be  furnished  as  pro- 
vided in  paragraph  .  . .  . ,  and  reinforcement  bars  will  be  furnished  when  required 
as  provided  in  paragraph 

STRUCTURAL  STEEL 

Based  on  "  Standard  Specifications  for  Structural  Steel  for  Buildings  "  of  the  American 
Society  for  Testing  Materials,  adopted  August  25,   1913- 

69.  Manufacture. — Structural  steel  may  be  made   by  either  the  open-hearth 
or  Bessemer  process.     Rivet  steel  and  plate  or  angle  material  over  f  inch  thick, 
which  is  punched,  shall  be  made  by  the  open-hearth  process.     The  steel  shall 


562  SPECIFICATIONS 

conform  in  all  respects,  not  specifically  mentioned  herein,  to  the  "  Standard 
Specifications  for  Structural  Steel  for  Buildings  "  of  the  American  Society  for 
Testing  Materials,  adopted  August  25,  1913,  and  tests  shall  be  made  as  provided 
in  said  specifications. 

70.  Chemical  and  Physical  Properties  of  Structural  Steel, — Steel  made  by  the 
Bessemer  process  shall  contain  not  more  than  o.io  per  cent  phosphorus  and  steel 
made  by  the  open-hearth  process  shall  contain  not  more  than  0.06  per  cent  phos- 
phorus.    All  structural  steel  shall  have  an  ultimate  tensile  strength  of  55,000  to 
65,000  pounds  per  square  inch;   an  elastic  limit,  as  determined  by  the  drop  of  the 
beam,  of  not  less  than  one-half  the  ultimate  tensile  strength;  a  minimum  per  cent 
of  elongation  in  8  inches  of  1,400,000  divided  by  the  ultimate  tensile  strength;  a 
silky  fracture;    and  capability  of  being  bent  cold  without  fracture  180°  flat  on 
itself  for  f-inch  material  and  under;  around  a  pin  having  a  diameter  equal  to  the 
thickness  of  the  test  piece  for  material  over  f  inch  to  and  including  if  inches; 
and  around  a  pin  having  a  diameter  equal  to  twice  the  thickness  of  the  test  piece 
for  material  over  i|  inches  in  thickness.     A  deduction  of  i  from  the  specified  per- 
centage of  elongation  will  be  allowed  for  each  f  inch  in  thickness  above  f-inch; 
and  a  deduction  of  2.5  will  be  allowed  for  each  ^  inch  in  thickness  below  j^  inch. 

71.  Chemical  and  Physical  Properties  of  Rivet  Steel. — Rivet  steel  shall  contain 
not  more  than  0.06  per  cent  phosphorus  nor  more  than  0.045  Per  cent  sulphur. 
It  shall  have  an  ultimate  tensile  strength  of  48,000  to  58,000  pounds  per  square 
inch;  an  elastic  limit  of  one-half  the  ultimate  tensile  strength;  a  minimum  per  cent 
of  elongation  in  8  inches  of  1,400,000  divided  by  the  ultimate  tensile  strength;  a 
silky  fracture;    and  capability  of  being  bent  cold  without  fracture  180°  flat  on 
itself. 

72.  Finish. — Finished  material  must  be  free  from  injurious  seams,  flaws,  or 
cracks,  and  have  a  workmanlike  finish. 

73.  Marking. — Every  finished  piece  of  steel  shall  be  stamped  with  the  melt 
or  blow  number,  except  that  small  pieces  may  be  shipped  in  bundles  securely  wired 
together  with  the  melt  or  blow  number  on  a  metal  tag  attached. 

74.  Test  Pieces. — (See  paragraph  40.) 

75.  Tests. — (See  paragraph  41.) 

76.  Payment. — (See  paragraph  43.) 

STEEL  REINFORCEMENT  BARS 

Based  on  "  Standard  Specifications  for  Billet-Steel  Concrete  Reinforcement  Bars  "  of  the 
American  Society  for  Testing   Materials,  adopted  August  25,   1913. 

77.  Manufacture. — Steel  may  be  made  by  either  the  open-hearth  or  Bessemer 
process  and  the  bars  shall  be  rolled  from  billets.     It  shall  conform  in  all  respects, 
not  specifically  mentioned  herein,  to  the  "  Standard  Specifications  for  Billet-steel 
Concrete  Reinforcement  Bars  "  of  the  American  Society  for  Testing  Materials 
adopted  August  25,  1913,  and  tests  shall  be  made  as  provided  in  said  specifications. 

78.  Type  of  Bars. — All  reinforcement  bars  shall  be  of    the    deformed  type. 
Bidders  shall  submit  samples  or  cuts  of  the  type  of  bar  they  propose  to  furnish. 

79.  Chemical  Properties. — Bars  of  steel  made  by  the  Bessemer  process  shall 
contain  not  more  than  o.io  per  cent  phosphorus,  and  not  more  than  0.05  per  cent 
phosphorus  if  made  by  the  open-hearth  process. 


SPECIAL  REQUIREMENTS  563 

80.  Physical  Properties. — Bars  of  steel  shall  have  an  ultimate  tensile  strength 
of  55,000  to  70,000  pounds  per  square  inch;   an  clastic  limit  of  not  less  than  33,000 
pounds  per  square  inch;  a  minimum  per  cent  of  elongation  in  8  inches  of  1,250,000 
divided  by  the  ultimate  tensile  strength;  and  capability  of  being  bent  cold  without 
fracture  180°  around  a  pin  having  a  diameter  equal  to  the  thickness  of  the  test 
piece  for  material  less  than  f  inch  in  thickness,  and  around  a  pin  having  a  diameter 
equal  to  twice  the  thickness  of  the  test  piece  for  material  of  |  inch  and  over  in  thick- 
ness.    For  each  increase  of  \  inch  in  diameter  or  thickness  above  f  inch  and  for 
each  decrease  of  -^  inch  in  diameter  or  thickness  below  ^  inch,  a  deduction  of 
i  will  be  allowed  from  the  specified  percentage  of  elongation. 

81.  Variation  in  Weight.— Bars  for  reinforcement   are   subject  to  rejection  if 
the  actual  weight  of  any  lot  varies  more  than  5  per  cent  over  or  under  the  theo- 
retical weight  of  that  lot. 

82.  Finish. — Finished  material  shall  be  free  from  injurious  seams,  flaws,  or 
cracks,  and  shall  have  a  workmanlike  finish. 

83.  Test  Pieces. — (See  paragraph  40). 

84.  Tests. — (See  paragraph  41.) 

85.  Payment. — (See  paragraph  43.) 

GRAY  IRON  CASTINGS 

Based  on  "  Standard  Specifications  for  Gray  Iron  Castings  "  of  the  American  Society  for 
Testing  Materials,  adopted  September  i,   1905. 

86.  Manufacture. — Castings  shall  be  of  tough  gray  iron  made  by  the  cupola 
process.     In  all  respects,  not  specifically  mentioned  herein  the  castings  shall  con- 
form to  the  "  Standard  Specifications  for  Gray  Iron  Castings  "  of  the  American 
Society  for  Testing  Materials,  adopted  September  i,  1901,  and  tests  shall  be  made 
as  provided  in  said  specifications. 

87.  Light  Castings,  Physical  and   Chemical  Properties.— Castings   having   any 
section  less  than  ^  inch  thick  shall  be  known  as  light  castings.     The  sulphur  con- 
tent shall  be  not  greater  than  0.08  per  cent.     The  minimum  breaking  load  of  a 
bar  i|  inches  in  diameter,  loaded  at  the  middle  of  a  1 2-inch  span,  shall  be  2500 
pounds.     The  deflection  shall  in  no  case  be  less  than  o.i  inch. 

88.  Heavy  Castings,   Physical    and    Chemical   Properties. — Castings  in  which 
no  section  is  less  than  2  inches  thick  shall  be  known  as  heavy  castings.     The  sul- 
phur content  shall  be  not  greater  than  0.12  per  cent.     The  minimum  breaking 
load  of  a  bar  i  i  inches  in  diameter,  loaded  at  the  middle  of  a  1 2-inch  span  shall  be 
3300  pounds.     The  deflection  shall  in  no  case  be  less  than  o.i  inch. 

89.  Medium  Castings,   Chemical  and  Physical    Properties. — Medium    castings 
are  those  not   included    under   "  light  "   or   "  heavy  "   castings.     Their  sulphur 
content  shall  be  not  greater  than  o.io  per  cent.     The  minimum  breaking  load  of  a 
bar  1 1  inches  in  diameter  loaded  at  the  middle  of  a  1 2-inch  span  shall  be  2900 
pounds.     The  deflection  shall  in  no  case  be  less  than  o.i  inch. 

90.  Finish. — All  castings  shall  be  true    to    pattern,  free  from  cracks,  flaws, 
porosity,  cold-shuts,  blow-holes  and  excessive  shrinkage  and  shall  have  a  work- 
manlike finish. 

91.  Test  Pieces. — (See  paragraph  40.) 

92.  Tests. — (See  paragraph  41.) 

93.  Payment. — (See  paragraph  43.) 


564  SPECIFICATIONS 


MALLEABLE  CASTINGS 

Based  on  "  Standard  Specifications  for  Malleable  Castings  "  of  the  American  Society  for 
Testing  Materials,  adopted  November  15,   1904. 

94.  Manujacture.— Malleable  iron  castings  may  be  made  by  the  open-hearth 
or  air  furnace  process.  In  all  respects  not  specifically  mentioned  herein  the  cast- 
ings shall  conform  to  the  "  Standard  Specifications  for  Malleable  Castings  "  of 
the  American  Society  for  Testing  Materials,  adopted  November  15,  1904,  and  tests 
shall  be  made  as  provided  in  said  specifications. 

95.  Chemical  and  Physical  Properties. — Castings  shall  contain  not  more  than 
0.06  per  cent  of  sulphur  nor  more  than  .0225  per  cent  of  phosphorus.     They  shall 
have  a  tensile  strength  of  not  less  than  40,000  pounds  per  square  inch  and  the  elonga- 
tion measured  in  2  inches  shall  not  be  less  than  i\  per  cent.     The  transverse 
strength  of  the  standard  test  bar  i  inch  square,  loaded  at  the  middle  of  a  1 2-inch 
span  shall  be  not  less  than  3000  pounds  per  square  inch;   and  the  deflection  shall 
be  at  least  \  inch. 

96.  Finish. — Castings  shall  be  true  to  pattern,  free  from  blemishes,  scale  and 
shrinkage  cracks,  and  shall  have  a  workmanlike  finish. 

97.  Test  Pieces. — (See  paragraph  40.) 

98.  Tests. — (See  paragraph  41.) 

99.  Payment. — (See  paragraph  43.) 

STEEL  CASTINGS 

Based  on  "  Standard  Specifications  for  Steel  Castings  "  of  the  American  Society  for  Testing 
Materials,  adopted  August  25,   1913. 

100.  Manufacture. — Steel   for   castings   may   be   made   by   the   open-hearth, 
crucible  or  Bessemer  process.     Castings  shall  be  annealed  unless  otherwise  speci- 
fied, and  in  all  respects  not  specifically  mentioned  herein  their  material  and  manu- 
facture shall  conform  to  the  Standard  Specifications  for  Steel  Castings  of  the  Amer- 
ican Society  for  Testing  Materials  adopted  August  25,  1913,  and  tests  shall  be  made 
as  provided  in  said  specifications. 

101.  Chemical  and  Physical  Properties. — Castings  shall  contain  not  more  than 
0.05  per  cent  of  phosphorus  nor  more  than  0.05  per  cent  of  sulphur.     Castings 
shall  be  classed  as  "  Hard,"  "  Medium  "  and  "  Soft  "  and  shall  have  the  following 
physical  properties: 

Hard.  Medium.  Soft. 

Tensile  strength,  pounds  per  square  inch 80,000  70,000  60,000 

Elastic  limit 36,000  31,500  27,000 

Elongation,  per  cent  in  2  inches 15                 18  22 

Contraction  of  area,  per  cent 20                 25  30 

102.  Finish.— Casting  shall  be  true  to  pattern,  free  from  blemishes,  flaws  or 
shrinkage  cracks.     Bearing  surfaces  shall  be  solid  and  no  porosity  shall  be  allowed 
in  positions  where  the  resistance  and  value  of  the  casting  for  the  purpose  intended 
will  be  seriously  affected  thereby. 

103.  Test  Pieces. — (See  paragraph  40.) 

104.  Tests. — (See  paragraph  41.) 

105.  Payment. — (See  paragraph  42.) 


SPECIAL  REQUIREMENTS  565 


CEMENT 

106.  The  Requirement. — It  is  required  that  there  be  furnished  in  accordance 
with  these  specifications  the  quantity  of  Portland  cement  set  forth  in  the  accom- 
panying advertisement,  f.  o.  b.  cars  at  the  place  named  by  the  bidder  in  his  pro- 
posal.    The  right  is  reserved  by to  increase  or  decrease  the  quantity 

to  an  extent  not  to  exceed  20  per  cent.     The  contractor  shall  store  cement  in  suf- 
ficient quantities  to  provide  for  the  completion  of  necessary  tests  thereon  before 
shipment  is  required. 

107.  Progress  Estimates  and  Payments. — At  the  end  of  each  calendar  month  the 
engineer  will  prepare  a  statement  of  the  amount  of  cement  delivered  to  that  date 
and  an  estimate  of  the  value  of  the  same  on  the  basis  of  the  unit  .price  named  in 
the  contract.     From  the  total  thus  computed  there  will  be  deducted  any  amount 

due from  the  contractor  under  the  terms  of  the  contract.     From  the 

amount  thus  determined  will  be  deducted  the  sum  of  all  previous  payments  and  the 
remainder  will  be  paid  to  the  contractor  on  approval  of  the  accounts. 

108.  Definition. — The  cement  shall  be  the  product  obtained  by  finely  pulver- 
izing clinker  produced  by  calcining  to  incipient  fusion,  an  'ntimate  mixture  of  prop- 
erly proportioned  argillaceous  and  calcareous  substances,  with  only  such  additions 
subsequent  to  calcining  as  may  be  necessary  to  control  certain  properties.     Such 
additions  shall  not  exceed  3  per  cent,  by  weight,  of  the  calcined  product. 

109.  Composition. — In  the  finished  cement,  the  following  limits  shall  not  be 
exceeded : 

Loss  on  ignition  for  15  minutes 4  per  cent 

Insoluble  residue i       " 

Sulphuric  anhydride  (SO5) 2       " 

Magnesia  (MgO) 5       " 

no.  Specific  Gravity. — The  specific  gravity  of  the  cement  shall  be  not  less  than 
3.10.  Should  the  cement  as  received  fall  below  this  requirement,  a  second  test 
may  be  made  upon  a  sample  heated  for  thirty  minutes  at  a  very  dull  red  heat. 

in.  Fineness. — At  least  78  per  cent  of  the  cement  by  weight,  shall  pass  through 
the  No.  200  sieve. 

112.  Soundness. — Pats  of  neat  cement  prepared  and  treated  as  hereinafter 
prescribed  shall  remain  firm  and  hard  and  show  no  sign  of  distortion,  checking, 
cracking,  or  disintegrating.     If  the  cement  fails  to  meet  the  prescribed  steaming 
test,  the  cement  may  be  rejected  or  the  steaming  test  repeated  after  seven  or  more 
days  at  the  option  of  the  engineer. 

113.  Time  of  Setting. — The  cement  shall  not  acquire  its  initial  set  in  less  than 
forty-five  minutes  and  must  have  acquired  its  final  set  within  ten-  hours. 

114.  Tensile  Strength. — Briquettes  made  up  of  i  part  cement  and  3  pnrts  stand- 
ard Ottawa  sand,  by  weight,  shall  develop  tensile  strength  per  square  inch  as  fol- 
lows: 

After  7  days,  i  day  in  moist  air,  6  days  in  water 200  pounds 

After  28  days,  i  day  in  moist  air,  27  days  in  water 300       " 

The  average  of  the  tensile  strengths  developed  at  each  age  by  the  briquettes 
in  any  set  made  from  one  sample  is  to  be  considered  the  strength  of  the  sample 


566  SPECIFICATIONS 

at  that  age,  excluding  any  results  that  are  manifestly  faulty.  The  average  strength 
of  the  briquettes  at  28  days  shall  show  an  increase  over  the  average  strength  at 
7  days. 

115.  Brand. — Bids  for  furnishing  cement  or  for  doing  work  in  which  cement  is 
to  be  used  shall  state  the  brand  of  cement  proposed  to  be  furnished  and  the  mill  at 
which  made.     The  right  is  reserved  to  reject  any  cement  which  has  not  established 
itself  as  a  high-grade  Portland  cement,  and  has  not  been  made  by  the  same  mill 
for  two  years  and  given  satisfaction  in  use  for  at  least  one  year  under  climatic  and 
other  conditions  at  least  equal  in  severity  to  those  of  the  work  proposed. 

116.  Packages. — The  cement  shall  be  delivered  in  sacks,  barrels,  or  other  suit- 
able packages  (to  be  specified  by  the  engineer),  and  shall  be  dry  and  free  from  lumps. 
Each  package  shall  be  plainly  labeled  with  the  name  of  the  brand  and  of  the  man- 
ufacturer.    A  sack  of  cement  shall  contain  94  pounds  net.     A  barrel  shall  con- 
tain 376  pounds  net.     Any  package  that  is  short  weight  or  broken  or  that  contains 
damaged  cement  may  be  rejected,  or  accepted  as  a  fractional  package,  at  the  option 
of  the  engineer.     If  the  cement  is  delivered  in  cloth  sacks,  the  sacks  used  shall  be 
strong  and  serviceable  and  securely  tied,  and  the  empty  sacks  will,  if  practicable, 
be  returned  to  the  contractor  at  the  point  of  delivery  of  the  cement.     On  final 

settlement  under  the  contract, cents  will  be  paid  the  contractor  for  each 

sack  furnished  by  him  in  accordance  with  the  above  requirements  and  not  returned 
in  serviceable  condition. 

117.  Inspection. — The  cement  shall  be  tested  in  accordance  with  the  standard 
methods  hereinafter  prescribed.     In  general  the  cement  will  be  inspected  and  tested 
after  delivery,  but  partial  or  complete  inspection  at  the  mill  may  be  called  for  in 
the  specifications  or  contract.     Tests  may  be  made  to  determine  the  chemical 
composition,   specific  gravity,  fineness,  soundness,   time  of  setting,  and  tensile 
strength,  and  a  cement  may  be  rejected  in  case  it  fails  to  meet  any  of  the  specified 
requirements.     An  agent  of  the  contractor  may  be  present  at  the  making  of  the 
tests  or  they  may  be  repeated  in  his  presence. 

CONTINUOUS  WOOD  STAVE  PIPE 

118.  Description. — The  pipe  shall  be  of  the  continuous-stave  metal-banded  type 
with  metal  tongues  driven  into  slots  in  the  ends  of  the  staves  to  form  the  butt 
joints.     The  alinement  and  profile  of  the  pipe  are  shown  in  the  drawings.     Each 
proposal  shall  be  accompanied  by  drawings  showing  clearly  detail  dimensions  of 
staves,  bands  and  tongues,  which  shall  comply  with  the  requirements  of  the  speci- 
fications.    Omission  of  drawings  from  proposals  or  any  uncertainty  as  to  detail 
dimensions  will  be  sufficient  cause  for  rejection. 

119.  Material. — All  material  of  whatever  nature  required  in  the  work  shall  be 
furnished  by  the  contractor.     The  price  bid  for  wood  staves  in  place  shall  include 
the  cost  of  all  necessary  tongues,  and  all  royalties  for  special  material  or  devices 
used  in  the  pipe  or  in  its  construction.     The  price  bid  for  bands  in  place  shall 
include  all  necessary  shoes  and  fastenings  and  asphaltum  coating,  and  all  royalties 
for  special  devices  used  in  the  pipe  or  in  its  construction. 

120.  Diameter  of  Pipe. — The  inside  diameter  of  the  pipe  shall  be inches, 

measured  after  completion  of  the  work.     No  diameter  at  any  point  shall  differ 
more  than  2  per  cent  from  the  average  diameter  of  the  pipe  at  said  point,  and 


SPECIAL  REQUIREMENTS  567 

the  average  of  the  vertical  and  horizontal  diameters  at  any  point  shall  not  be 
less  than  the  specified  diameter. 

121.  Staves. — All  lumber  used  in  staves  shall  be  Douglas  fir  or  redwood.     It 
shall  be  sound,  straight-grained,  and  free  from  dry  rot,  checks,  wind  shakes,  wane, 
and  other  imperfections  that  may  impair  its  strength  or  durability.     Redwood 
shall  be  clear  and  free  from  sap.     In  Douglas  fir  sap  will  not  be  allowed  on  more 
than  10  per  cent  of  the  inside  face  of  any  stave  and  in  not  more  than  10  per  cent 
of  the  total  number  of  pieces;    sap  shall  be  bright  and  shall  not  occur  within  4 
inches  of  the  ends  of  any  piece;   pitch  seams  will  be  permitted  in  not  over  10  per 
cent  of  the  total  number  of  pieces,  if  showing  on  the  edge  only,  and  if  not  longer 
than  4  inches  nor  wider  than  YS  inch;    no  through  knots  nor  knots  at  edge  nor 
within  6  inches  of  ends  of  staves  will  be  allowed;    sound  knots  not  exceeding  | 
inch  in  diameter,  not  falling  within  the  above  limitations,  nor  exceeding  three  within 
a  lo-foot  length  will  be  accepted.     All  lumber  used  shall  be  seasoned  by  not  less 
than  sixty  days'  air  drying  in  open  piles  before  milling  or  by  thorough  kiln  drying. 
All  staves  shall  have  smooth  planed  surfaces  and  the  inside  and  outside  faces  shall 
be  accurately  milled  to  the  required  circular  arcs  to  fit  a  standard  pattern  provided 
by  the  contractor.     Staves  shall  be  trimmed  perfectly  square  at  ends  and  the  slots 
for  tongues  shall  be  in  exactly  the  same  relative  position  for  all  ends  and  according 
to  detail  drawings  furnished  by  the  contractor.     Staves  shall  have  an  average  length 
of  not  less  than  15  feet  6  inches  and  not  more  than  i  per  cent  of  the  staves  shall 
have  a  length  of  less  than  9  feet  6  inches.     No  staves  shorter  than  8  feet  will  be 

accepted.     The  finished  thickness  of  staves  shall  not  be  less  than inches. 

All  staves  delivered  on  the  work  in  a  bruised  or  injured  condition  will  be  rejected. 
If  staves  are  not  immediately  used  on  arrival  at  the  site  of  the  work,  they  shall  be 
kept  under  cover  until  used. 

122.  Bands. — A  band  shall  consist  of  one  complete  fastening  and  shall  include 
the  bolts,  shoes,  nuts  and  washers  necessary  to  form  same. 

123.  Band  Spacing. — The  distance  center  to  center  of  bands  shall  be  as  marked 
on  the  profile,  except  that  where  the  spacing  as  marked  is  such  as  to  make  the  dis- 
tances from  bands  to  the  ends  of  staves  more  than  4  inches  extra  bands  shall  be 
used  to  keep  such  distances  within  4  inches. 

124.  Bolts. — All  bolts  shall  be  of inch  diameter  steel  and  shall  conform 

to  the  following  specifications:    (See  specifications  for  structural  steel.)     Bolts 
may  have  either  button  or  bolt  heads.     They  shall  be  at  least  as  strong  in  thread 
as  in  body  and  threads  shall  permit  the  nut  to  run  freely  for  the  entire  length  of 
thread.      Nuts    shall    be  of  such  thickness    as  to  insure  against  stripping    of 
threads. 

125.  Shoes. — There  shall  be malleable  iron  shoes  to  each  band.     Shoes 

shall  fit  accurately  to  the  outer  surface  of  the  pipe  and  shall  have  the  dimensions 
shown  on  the  drawing,  or  the  contractor  may  submit  for  approval  a  drawing  or 
sample  of  some  other  type  of  shoe  which  he  may  desire  to  furnish.     If  required, 
such  shoe  shall  be  shown  under  suitable  test  to  be  stronger  than  the  bolt.     The 
material  for  shoes  shall  conform  to  the  following  specifications:    (See  standard 
specifications  for  malleable  castings.) 

126.  Tongues. — Shall  be  of  galvanized  steel  or  iron inch  thick  and  ...  ... 

wide.     Their  length  shall  be  such,  that  when  in  place,  they  will  penetrate  into  the 
sides  of  the  adjacent  staves  without  undue  injury.     The  tongues  and  slots  shall  be 


568  SPECIFICATIONS 

so  proportioned  as  to  insure  a  tight  fit  of  the  tongues  into  the  slots  without  danger 
of  splitting  the  staves. 

127.  Coating  of  Bands. — The  bands  shall  be  coated  by  being  dipped  when  hot 
in  a  mixture  of  pure  California  asphalt,  or  equivalent.     Bolts  shall  be  bent  to  the 
required  arc  before  dipping.     If  the  bands  are  dipped  cold  they  shall  be  left  in  the 
hot  bath  a  sufficient  length  of  time  to  insure  that  they  have  acquired  the  tem- 
perature of  the  asphalt.     This  coating  shall  be  so  proportioned  and  applied  that 
it  will  form  a  thick  and  tough  coating  free  from  tendency  to  flow  or  become  brittle 
under  the  range  of  temperature  to  which  it  will  be  subjected.     Where  the  pipe  is 
uncovered  and  exposed  to  the  full  range  of  atmospheric  temperatures,  not  less  than 
7  per  cent  and  not  more  than  10  per  cent  of  pure  linseed  oil  shall  be  mixed  with  the 
asphalt. 

128.  Erection. — The  pipe  shall  be  built  in  a  workmanlike  manner.     The  ends 
of  adjoining  staves  shall  break  joint  at  least  3  feet.     The  staves  shall  be  driven  in 
such  a  manner  as  to  avoid  any  tendency  to  cause  wind  in  the  pipe  and  the  required 
grade  and  alinement  must  be  maintained.     Staves  shall  be  well  driven  to  produce 
tight  butt  joints,  driving  bars  or  other  suitable  means  being  used  to  avoid  marring 
or  damaging  staves  in  driving.     In  rounding  out  the  pipe,  care  shall  be  exercised 
to  avoid  damage  by  chisels,  mauls  or  other  tools.     The  pipe  shall  be  rounded  out 
to  produce  smooth  inner  and  outer  surfaces.     Bands  shall  be  accurately  spaced 
and  placed  perpendicular  to  the  axis  of  the  pipe.     Shoes  shall  be  placed  so  as  to 
cover  longitudinal  joints  between  staves  and  bear  equally  on  two  staves  as  nearly 
as  practicable.     They  shall  be  placed  alternately  on  opposite  sides  of  the  pipe 
so  as  to  be  out  of  line  and  cover  successively  on  each  side  at  least  three  joints. 
Shoes  shall  not  be  allowed  to  cover  the  butt  joints.     Bolts  shall  be  hammered 
thoroughly  into  the  wood  to  secure  a  bearing  on  60  degrees  of  the  circumference 
of  the  bolt.     All  kinks  in  bolts  shall  be  carefully  hammered  out.     Bands  shall  be 
back-cinched  to  the  satisfaction  of  the  engineer  so  as  to  produce  the  required  initial 
compressive  stresses  in  the  staves.     All  metal  work  shall  be  handled  with  reason- 
able care  so  as  to  avoid  injury  to  the  coating  as  much  as  possible.     In  hammer- 
ing shoes  into  place  they  shall  be  struck  so  as  to  avoid  deformation  or  injury. 
After  erection  the  contractor  shall  retouch  all  metal  work,  where  abraded,  with  an 
asphaltum  paint  satisfactory  to  the  engineer. 

129.  Painting. — After  erection  and  while  the  pipe  is  dry  the  entire  outer 
surface  shall  be  given  a  coat  of  refined  water-gas  tar,  followed  by  a  coat  of  refined 
coal-gas  tar,  thinned  with  distillate,  applied  with  brushes  or  sprayed  on  with  air 
pressure.     Before  application  of  the  paint  the  surface  of  the  pipe  shall  be  thoroughly 
cleaned  of  dirt,  dust  and  foreign  matter  of  every  kind.     All  checks,  cracks  and  sur- 
face irregularities  of  every  kind  shall  be  thoroughly  filled  with  paint.     The  finished 
thickness  of  the  coating  shall  be  not  less  than  ^  inch.     The  cost  of  all  work  under 
this  paragraph  shall  be  included  in  the  price  bid  for  pipe  in  place. 

130.  Inspection. — Final  inspection  of  materials,  as  well  as  erection  will  be  made 
on  the  work,  but  if  the  contractor  so  desires,  preliminary  inspection  of  staves  may 
be  made  at  the  mill  at  the  contractor's  expense.     Mill  inspection,  however,  shall 
not  operate  to  prevent  the  rejection  of  any  faulty  material  on  the  work.     Tests 

of  metal  work  will  be  made  at  the  point  of  manufacture  by at  his  own 

expense;    or  they  may  be  made  at  the  plant  by  the  contractor  or  his  employees 
acting  under  the  direction  of  the  engineer  or  his  representative;   or  certified  tests 


SPECIAL  REQUIREMENTS  569 

may,  at  the  option  of  the  engineer,  be  accepted  in  lieu  of  the  above-mentioned 
tests.  The  contractor  shall  provide,  at  his  own  expense,  the  necessary  test  pieces, 
and  shall  notify  the  engineer  or  his  representatives  when  these  pieces  are  ready 
for  testing.  All  test  bars  and  test  pieces  shall  be  marked  so  as  to  indicate  clearly 
the  material  that  they  represent,  and  shall  be  properly  boxed  and  prepared  for  ship- 
ment if  required. 

131.  Tests  of  Pipe.  —  On  completion  of  the  work,  or  as  soon  as  possible  there- 
after, the  contractor  shall  make  a  full  pressure  test  of  the  pipe,  water  being  furnished 
therefor  by  ............     All  leaks  found  at  the  time  of  the  test  shall  be  made 

tight  by  the  contractor.     If  the  leakage  is  not  so  large  as  to  endanger  the  founda- 
tion of  the  pipe,  the  pipe  shall  be  kept  under  full  pressure  for  two  days  before  plug- 
ging of  leaks  is  started  in  order  to  allow  the  wood  to  become  thoroughly  saturated. 
The  cost  of  making  the  test,  except  furnishing  water,  shall  be  borne  by  the  con- 
tractor. 

132.  Payments.  —  At  the  end  of  each  calendar  month  50  per  cent  of  the  price 
for  material  in  place  shall  be  paid  to  the  contractor  for  material  delivered  on  the 
work;   25  per  cent  additional  shall  be  paid  after  erection  and  preliminary  cinching; 
and  the  remainder  shall  be  paid  after  final  test  and  acceptance  of  the  pipe  by  the 
engineer  and  when  the  terms  of  the  contract  shall  have  been  fully  complied  with  to 
the  satisfaction  of  the  engineer,  and  a  release  of  all  claims  against  ..............  , 

under,  or  by  virtue  of  the  contract,  shall  have  been  executed  by  the  contractor. 

MACHINE  BANDED  WOOD  STAVE  PIPE 

133.  Description.  —  The   pipe    shall  be  of   the    jointed,    wood-stave,   machine 
banded  type. 

134.  Lengths  of  Pipe  Sections.  —  Pipe  shall  be  furnished  in  lengths  of  10  to  20 
feet  and  the  average  length  shall  be  not  less  than  16  feet.     Shorter  sections  shall  be 
furnished  only  if  required  for  making  sharp  curves  in  which  case  the  lengths  shall 
not  be  more  than  i  foot  shorter  than  will  be  required  to  keep  the  joint  opening 
at  the  outside  of  the  cur/e  due  to  throw  within  a  limit  of  Y§  inch. 

135.  Material.  —  All  material  of  whatever  nature  required  in  the  manufacture 
of  the  pipe  in  accordance  with  these  specifications  shall  be  furnished  by  the  con- 
tractor. 

136.  Diameter  of  Pipes.  —  The  diameters  of  pipes  shsdl  be  as  listed  in  the  sched- 
ules.    No  diameter  of  any  pipe  shall  differ  more  than  i  per  cent  from  the  specified 
diameter  of  the  pipe,  and  the  average  of  the  vertical  and  horizontal  diameters  at 
any  point  shall  not  be  less  than  the  specified  diameter. 

137.  Thickness  of  Staves.  —  The  finished  thickness  of  staves  shall  be  as  follows: 


4  to    6  inches 

I  -J 

8  to  10     " 

ll 

I  2  tO   14       '  ' 

16  to  18     "       ...              

jl 

2O  tO  24       " 

.    Il5 

138.  Lumber  for  Staves.  —  All  lumber  used  in  staves  shall  be  Douglas  fir  or  red- 
wood.    It  shall  be  sound,  straight-grained,  and  free  from  dry  rot,  checks,  wind 


570  SPECIFICATIONS 

shakes,  wane  and  other  imperfections  that  may  impair  its  strength  or  durability. 
Redwood  shall  be  clear  and  free  from  sap.  In  Douglas  fir  sap  will  not  be  allowed 
on  more  than  10  per  cent  of  the  inside  face  of  any  stave  and  in  not  more  than  10 
per  cent  of  the  total  number  of  pieces;  sap  shall  be  bright  and  shall  not  occur 
within  4  inches  of  the  ends  of  any  piece;  pitch  seams  will  be  permitted  in  not  over 
10  per  cent  of  the  total  number  of  pieces,  if  showing  on  the  edge  only,  and  if  not 
longer  than  4  inches  nor  wider  than  Y&  inch;  no  through  knots  or  knots  at  edges  or 
within  6  inches  of  ends  of  staves  will  be  allowed;  sound  knots  not  exceeding  \  inch 
in  diameter,  not  falling  within  the  above  limitations,  nor  exceeding  three  within 
a  lo-foot  length  will  be  accepted.  All  lumber  used  shall  be  seasoned  by  not  less 
than  sixty  days'  air  drying  in  open  piles  before  milling  or  by  thorough  kiln  drying. 
All  staves  shall  have  smooth  planed  surfaces  and  the  inside  and  outside  faces  shall 
be  accurately  milled  to  the  required  circular  arcs. 

139.  Banding.  —  Size  and  spacing  of  banding  wire  shall  be  adjusted  for  a  working 
stress  of  12,000  pounds  per  square  inch  on  the  wire.  The  spacing  shall  in  no  case 
be  greater  than  4  inches  center  to  center  of  wires,  nor  greater  than  will  produce  a 
pressure  of  wire  on  the  wood  of  800  pounds  per  square  inch  as  calculated  from  the 

pRf 
formula  B=   /n_,\>  where  B  =  pressure  on  wood  in  pounds  per  square    inch; 


p  =  water  pressure  in  pounds  per  square  inch;  /=  spacing  of  wire  in  inches;  R  = 
inside  radius  of  pipe  in  inches;  r  —  radius  of  wire  in  inches;  and  /  =  thickness  of 
staves  in  inches.  No  wire  smaller  than  No.  8  U.  S.  Standard  gage  shall  be  used. 
Wire  shall  be  of  medium  steel  double-galvanized  and  shall  have  an  ultimate  tensile 
strength  of  55,000  to  65,000  pounds  per  square  inch,  and  capability  of  being  bent 
flat  on  itself  without  fracture.  The  bidder  shall  state  in  his  proposal  the  size  of 
banding  wire  he  proposes  to  furnish. 

140.  Joints.  —  Inserted  joint  pipe  shall  be  furnished  for  diameters  of  12  inches 
and  less  and  for  heads  not  exceeding  50  feet.     For  pipes  of  larger  diameter  than 
12  inches  and  for  all  pipes  under  more  than  50  feet  head,  wood  sleeve  collars  shall 
be  furnished.     The  banding  on  collars  shall  be  50  per  cent  stronger  than  the 
banding  on  the  pipe. 

141.  Individual  Bands.  —  Individual  bands  shall  be  used  on  all  collars  for  pipe 
1  2  inches  and  greater  in  diameter.     The  smallest  bolts  used  shall  be  f  inch  in  diam- 
eter.    The  bolt  shall  have  an  ultimate  tensile  strength  of  55;ooo  to  65,000  pounds 
per  square  inch;  an  elastic  limit  of  one-half  the  ultimate  tensile  strength  and 
capability  of  being  bent  back  flat  on  itself  without  fracture.     The  shoes  shall  be 
malleable  iron  and  shall  be  stronger  than  the  bolts,  with  sufficient  bearing  on  the 
wood  at  the  tail  to  prevent  injurious  indentation  in  cinching.     The  shoes  shall 
be  sound  and  free  from  blow-holes,  and  shall  have  an  ultimate  tensile  strength  of 
not  less  than  40,000  pounds  per  square  inch.     Bidders  shall  submit  samples  or 
drawings  of  the  type  of  shoe  they  propose  to  furnish. 

142.  Coating.  —  After  manufacture  the  outside  of  the  pipe  and  collars  shall  be 
dipped  in  a  bath  of  hot  coal  tar  and  asphaltum.     Previous  to  dipping  the  collars 
in  coal  tar  and  asphaltum  they  shall  be  dipped  for  a  depth  of  i  inch  at  each  end  for 
a  period  of  ten  minutes  in  a  bath  of  creosote.     Care  should  be  exercised  to  keep 
the  coal  tar  and  asphaltum  from  the  tenon  ends  and  inside  surfaces  and,  if  neces- 
sary, the  tenons  shall  be  wrapped  with  paper  while  being  dipped.     After  dipping 
the  pipe  and  collars  shall  be  rolled  in  fine  sawdust  while  the  coating  is  still  soft. 


SPECIAL  REQUIREMENTS  571 

143.  Inspection. — Inspection  of  pipe  will  be  made  at  the  mill,  but  the  manufac- 
turer will  be  held  responsible  for  any  damage  in  transit  caused  by  improper  loading 
of  the  pipe. 

144.  Marking. — Each  section  of  pipe  shall  be  plainly  marked  on  the  inside  at 
one  end,  showing  the  head  for  which  the  section  was  wound,  and  the  number  of  the 
banding  wire  used. 

LAYING  MACHINE  BANDED  WOOD  STAVE  PIPE 

145.  Point  of  Delivery. — Pipe  will  be  delivered  f.  o.  b.  cars  at in 

lengths  of  12  to  20  feet.     The  contractor  shall  unload  cars  at  once  and  will  be  held 
responsible  for  all  demurrage  charges. 

146.  Handling. — In  unloading  and  hauling,  the  pipe  shall  be  handled  carefully. 
To  avoid  injury  to  the  ends,  the  pipe  should  not  be  carried  by  means  of  sticks 
inserted  in  the  ends.     The  contractor  will  be  held  responsible  for  any  damage  due 
to  careless  handling. 

147.  Laying. — The  pipe  should  be  laid  with  coupling  or  mortise  end  in  the 
direction  of  the  laying.     Care  should  be  taken  in  inserting  the  tenon  to  see  that  it 
is  started  around  the  entire  circumference  and  the  joint  should  first  be  driven 
lightly  until  it  is  assured  that  a  good  connection  is  being  made,   then  drive  to  the 
shoulder.     The  bands  on  couplings  should  not  be  fully  cinched  until  the  joint 
has  been  driven  home.     The  bands  on  couplings  should  be  placed  symmetrically 
about  the  middle  of  the  coupling  and  in  cinching  a  few  turns  should  be  given  alter- 
nately to  each  band  in  order  to  maintain  approximately  the  same  tension  on 
each. 

148.  Alincment  and  Grade. — In  laying  the  pipe  true  alinement  and.  grade  must 
be  maintained.     If  necessary,  short  sections  of  pipe  shall  be  used  for  making  sharp 
curves  and  the  pipe  shall  be  anchored  by  staking  the  outside  at  each  joint.     Curves 
shall  be  made  by  driving  the  joint  on  a  tangent  and  then  springing  into  place. 

149.  Fittings. — Elbows,  tees  and  other  special  fittings  shall  be  securely  anchored 
in  concrete  as  directed  by  the  engineer. 

150.  Tests. — After  the  pipe  has  been  laid  it  shall  be  subjected  to  tne  full  pres- 
sure of  water  and  the  contractor  shall  stop  all  leaks.     Damages  to  the  pipe  caused 
by  the  pressure  of  water,  that  are  due  to  improper  or  careless  laying  shall  be 
repaired  by  the  contractor,  but  he  shall  not  be  responsible  for  damages  due  to  defec- 
tive manufacture.     If  the  leakage  is  not  so  large  as  to  endanger  the  foundation 
of  the  pipe,  it  shall  be  kept  under  full  pressure  for  two  days  before  plugging  of  leaks 
is  started  in  order  to  allow  the  wood  to  become  thoroughly  saturated.     Water 

for  tests  will  be  furnished  by ,  but  the  expense  of  making  the 

test,  except  furnishing  water,  shall  be  borne  by  the  contractor. 

151.  Payments. — On  the  completion  of  a  pipe  line per  cent  of  the  con- 
tract price,  on  the  basis  of  the  unit  price  bid  per  linear  foot  of  pipe  in  place,  will  be 
made.     The  remainder  will  be  paid  after  final  test  and  acceptance  of  the  pipe  by 
the  engineer,  and  when  the  terms  of  the  contract  shall  have  been  fully  complied 

with  to  the  satisfaction  of  the  engineer,  and  a  release  of  all  claims  against 

....  under,  or  by  virtue  of  the  contract,  shall  have  been  executed  by  the  con- 
tractor. 


572 


SPECIFICATIONS 


STEEL  PIPE 

152.  Description. — Steel  pipe  may  be  either  of  the  lockbar  or  riveted  steel 

type.     Riveted  steel  pipe  shall  have  <  I  courses.     Circular  seams  may 

i      taper       j 

{  triple  \  ^ 

I  double 

shall  submit  with  his  bid  a  drawing  showing  details  of  joints,  size  and  spacings  of 
rivets,  etc.  Failure  to  submit  such  drawing  will  be  sufficient  cause  for  rejection 
of  the  bid. 

153.  Thickness  of  Metal. — The  thickness  of  steel  sheets  shall  be  as  follows: 


Length,  Feet. 

Thickness,  Inches. 

Head,  Feet. 

Riveted. 

Lockbar. 

154.  Planing  and  Scarfing. — When  necessary  the  edges  of  plates  shall  be  pre- 
pared for  caulking  by  planing  and  scarfing  at  the  factory. 

155.  Riveting. — The  riveting  and  other  details  of  longitudinal  seams  shall  be 
designed  to  withstand  the  heads  given  in  paragraph  198.     The  rivets  for  cir- 
cular joints  shall  be  of  the  same  size  as  for  longitudinal  seams.     The  intensity  of 
working  stress  on  rivets  shall  be  7500  pounds  per  square  inch  in  shear  and  15,000 
pounds  per  square  inch  in  bearing  on  riveted  plates.     All  rivet  spacing  shall  be 
arranged  to  give  the  greatest  possible  efficiency  of  joint.     Size  of  rivets  and  rivet 
spacing  shall  be  submitted  to  the  engineer  for  approval.     All  riveting  shall  be  done 
in  the  field,  but  sufficient  of  the  work  done  with  different  templates  must  be 
assembled  at  the  shop  to  prove  the  work  correct.     (When  appropriate  shop  rivet- 
ing should  be  specified.) 

156.  Punching. — Rivet  holes  may  be  punched  and  shall  be  no  larger  than  is 
necessary  to  pass  the  required  size  of  rivet.     Drift  pins  shall  not  be  used  except 
for  bringing  together  the  several  parts,  and  drifting  with  such  force  as  to  distort 
the  holes  will  not  be  allowed.     Wrongly  punched  plates  shall  not  be  corrected  by 
plugging  the  holes  and  a  re-punching,  but  shall  be  rejected.     All  burrs  and  ragged 
edges  on  plates  shall  be  smoothed  off  before  leaving  the  shop.     All  punching  shall 
be  done  at  the  shop  before  shipment. 

157.  Material. — All  steel  shall  be  made  by  the  open-hearth  process.     Steel  for 
plates  shall  be  of  the  grade  known  as  "  boiler  plate."     Steel  for  rivets  shall  be  of  the 
grade  known  as  "  boiler  rivet  steel." 


SPECIAL  REQUIREMENTS  573 

158.  Chemical  and  Physical  Properties  of  Boiler  Plate  Steel. — Boiler  plate  steel 
shall  contain  not  more  than  .05  per  cent  phosphorus,  .05  per  cent  sulphur,  and  from 
0.30  to  0.60  per  cent  manganese.     It  shall  show  an  ultimate  tensile  strength  of 
55,000  to  65,000  pounds  per  square  inch;   an  elastic  limit  of  not  less  than  one-half 
the  ultimate  tensile  strength;  an  ultimate  elongation  in  8  inches  of  not  less  than 
1,500,000  divided  by  the  ultimate  tensile  strength;    and  capability  of  being  bent, 
cold  or  quenched,  180°  flat  without  fracture.     The  steel  shall  be  in  all  respects 
such  as  to  stand  punching,  caulking  and  riveting  without  showing  the  least  tendency 
to  crack.     Plates  shall  withstand,  without  cracking  of  the  material,  a  drift  test 
made  by  driving  a  pin  into  a  f-inch  hole,  enlarging  same  to  a  diameter  of  i  inch. 
In  all  respects  not  covered  in  these  specifications  boiler  plate  steel  shall  conform 
to  the  "  Standard  Specifications  for  Boiler  Steel  "  of  the  American  Society  for 
Testing  Materials,  adopted  August  25,  1913. 

159.  Chemical  and  Physical  Properties  of  Rivet  Steel. — Steel  for  rivets  shall  con- 
tain not  more  than  0.04  per  cent  of  phosphorus,  0.45  per  cent  sulphur,  and  from 
0.30  to  0.50  per  cent  of  manganese.     It  shall  show  an  ultimate  tensile  strength  of 
45,000  to  55,000  pounds  per  square  inch;   an  elastic  limit  of  not  less  than  one-half 
the  ultimate  tensile  strength;   an  ultimate  elongation  in  8  inches  of  not  less  than 
1,500,000  divided  by  the  ultimate  tensile  strength,  but  need  not  exceed  30  per  cent; 
and  capability  of  being  bent,  cold  or  quenched,  180°  flat  without  fracture.     Rivet 
rounds  shall  be  tested  of  full  size  as  rolled.     In  all  respects  not  covered  in  these 
specifications  steel  for  rivets  shall  conform  to  the  "  Standard  Specifications  for 
Boiler  Rivet  Steel  "  of  the  American  Society  for  Testing  Materials,  adopted 
August  25,  1913. 

1 60.  Marking. — Each  plate  shall  be  distinctly  stamped  with  its  melt  or  slab 
number.     Rivet  steel  may  be  shipped  in  securely  fastened  bundles  with  melt 
number  stamped  on  a  metal  tag  attached.     Plates  and  other  parts  shall  be  plainly 
marked  for  identification  and  assembly  in  the  field. 

161.  Test  Pieces. — (See  paragraph  40.) 

162.  Test  of  Material. — (See  paragraph  41.) 

163.  Erection. — Erection  of  pipe  shall  be  commenced  at  the  point  directed 
by  the  engineer.     The  contractor  shall  haul  all  material  and  distribute  same  along 
the  trench  and  shall  furnish  a  compressed  air  plant  and  full  equipment  for  air  rivet- 
ing, and  all  other  equipment,  tools  and  supplies  required  for  the  erection  of  the  pipe 
and  completion  for  service.     The  pipe  shall  be  carefully  caulked  and  painted  as 
the  work  progresses.     The  work  of  assembling,  riveting  and  caulking  shall  be  done 
by  workmen  experienced  in  this  line.     Riveting  shall  show  first  class  workmanship, 
rivet  heads  shall  be  full  and  concentric  with  the  body  of  the  rivet,  and  the  rivet 
shall  completely  fill  the  hole  and  thoroughly  pinch  the  connected  pieces  together. 
Rivets  that  are  loose  or  have  defective  heads  shall  be  removed  and  other  rivets 
substituted  therefor. 

164.  Painting. — Inside  and  outside  of  pipe  shall  be  covered  with  three  coats 
of  a  reliable  brand  of  asphalt  paint  which  shall  be  subject  to  the  approval  of  the 
engineer.     Before  painting  all  surfaces  shall  be  thoroughly  cleaned  by  scrubbing 
with  wire  brushes  or  other  means  as  directed  by  the  engineer.     All  riveted  joints 
shall  be  painted  before  riveting.     All  paint  shall  be  applipd  while  the  pipe  is  warm 
and  thoroughly  dry. 

165.  Defective  Work.— The  contractor  shall  guarantee  the  material  and  work- 


574  SPECIFICATIONS 

manship  furnished  by  him  to  he  free  from  defects  of  material  and  construction, 

and  he  shall  replace  free  of  cost  to any  material  that  shall  develop 

faults  during  construction  or  tests. 

166.  Test  of  Pipe. — On  completion  of  erection,  or  as  soon  as  possible  thereafter, 
the  contractor  shall  make  a  full  pressure  test  of  the  pipe,  water  therefor  being 

furnished  by The  pipe  shall  be  water-tight  under  this  test  and 

the  contractor  shall  correct  any  defects  that  develop. 

JOINTED  REINFORCED  CONCRETE  PIPE 

167.  Description. — The  pipe  shall  be  composed  of  concrete  reinforced  with  steel 

rods  or  wire  and  built  in  vertical  forms  in  lengths  of feet;    the  sections 

being  connected  in  the  trench  by  concrete  collars  reinforced  with  steel. 

1 68.  Diameter  of  Pipe. — The  inside  diameter  of  the  pipe  shall  be inches 

and  no  diameter  shall  differ  more  than  0.5  per  cent  from  the  specified  diameter  of 
the  pipe.     Each  section  of  pipe  shall  be  a  true  right  cylinder  with  the  plane  of  the 
ends  perpendicular  to  the  axis  of  the  pipe. 

169.  Thickness  of  Shell. — The  shell  of  the  pipe  shall  have  a  thickness  of 

inches  which  shall  be  uniform  around  the  entire  circumference.     In  no  case  will  a 
variation  of  more  than  10  per  cent  from  the  specified  thickness  be  allowed. 

170.  Manufacture. — The  concrete  shall  be  thoroughly  mixed  in  a  mechanical 
batch  mixer.     It  shall  be  deposited  in  such  a  manner  that  no  separation  of  ingre- 
dients will  occur  and  suitable  tools  shall  be  used  to  thoroughly  settle  the  concrete 
and  produce  smooth  surfaces.     Great  care  shall  be  exercised  to  maintain  proper 
spacing  of  the  reinforcing  rods.     No  pipe  shall  be  manufactured  when  the  tempera- 
ture of  the  atmosphere  is  above  90°,  except  by  permission  of  the  engineer.     During 
manufacture  the  concrete  and  forms  shall  be  protected  from  the  direct  rays  of  the 
sun,  and  for  five  days  thereafter  the  sections  shall  be  kept  both  moist  and  cov- 
ered, and  they  shall  be  kept  moist  for  fifteen  days  additional.     Manufacture  shall 
not  be  carried  on  in  freezing  weather,  except  in  a  heated  enclosure  and  the  sections 
of  pipe  shall  be  prevented  from  freezing.     Immediately  after  removal  of  the  forms 
all  defects  in  the  surface  of  the  concrete  shall  be  smoothed  up  with  a  i  to  i  mixture 
of  cement  and  fine  sand,  especial  care  being  taken  to  produce  smooth  interior 
surfaces.     Forms  shall  not  be  removed  in  less  than  twenty-four  hours  after  the 
concrete  has  been  poured. 

171.  Forms. — The  forms  used  shall  be  subject  to  the  approval  of  the  engineer. 
All  steel  forms  are  preferred,  but  wooden  forms  with  steel  linings  may  be  used  pro- 
vided the  desired  results  can  be  obtained  therewith.     Forms  shall  be  strong  and 
rigid  with  sufficient  bracing  to  prevent  warping  in  handling,  or  pouring  concrete. 
They  shall  be  provided  with  suitable  attachments  for  making  the  joint  grooves  at 
the  ends  in  accordance  with  the  drawings.     A  sufficient  number  of  forms  shall  be 

provided  to  allow  the  manufacture  of  not  less  than sections  of  pipe  per  day, 

or  such  additional  number  as  may  be  necessary  to  complete  the  work  within  the 
specified  time. 

172.  Reinforcement. — The  transverse  reinforcement  shall   consist   of  medium 
steel  rods  or  wire  and  shall  be  spaced  as  shown  on  the  drawings.     Sufficient  longi- 
tudinal reinforcement  shall  be  used  to  fasten  the  transverse  rods  and  hold  them 
rigidly  in  place.     The  transverse  reinforcement  may  be  either  individual  rods 


SPECIAL  REQUIREMENTS  575 

welded  or  lapped  and  wired  at  the  ends  for  a  length  of  24  diameters,  or  it  may  be 
wound  in  helical  coils.     The  latter  method  is  preferred  where  its  use  is  practicable. 

173.  Steel. — Steel  may  be  made  by  either  the  open-hearth  or  Bessemer  process. 
It  shall  contain  not  more  than  o.i  per  cent  phosphorus  if  made  by  the  Bessemer 
process  and  not  more  than  0.05  per  cent  if  made  by  the  open-hearth  process.     It 
shall  have  an  ultimate  tensile  strength  of  55,000  to  70,000  pounds  per  square  inch; 
an  elastic  limit    not  less  than  33,000  pounds  per  square  inch;    a  minimum  per 
cent  of  elongation  in  8  inches  of  1,400,000  divided  by  the  ultimate  tensile  strength; 
and  capability  of  being  bent  cold  without  fracture  180°  around  a  pin  having  a 
diameter  equal  to  the  thickness  of  the  test  piece.     Bars  or  wire  will  be  subject  to 
rejection  if  the  actual  weight  of  any  lot  varies  more  than  5  per  cent  over  or  under 
the  theoretical  weight  of  that  lot. 

174.  Concrete. — Concrete  shall  be  composed  of  cement,  sand  and  gravel,  well 
mixed  and  brought  to  a  proper  consistency  by  the  addition  of  water.     The  pro- 
portions will  depend  upon  the  nature  of  component  materials  and  upon  the  head  of 
water  that  the  pipe  will  be  subjected  to,  but  will  vary  in  general  from  one  part 
cement  to  five  parts  aggregate,  to  one  part  cement  to  six  parts  of  aggregate.     The 
contractor  shall  not  be  entitled  to  any  extra  compensation  by  reason  of  such  vari- 
tions. 

175.  Cement. — Cement  for  concrete  will  be  furnished  to  the  contractor.     The 
contractor  shall  give  the  engineer  not  less  than  thirty  days'  notice  in  writing  of 
his  cement  requirements,  which  shall  be  stated,  so  far  as  practicable  in  quantities 
not  less  than  single  car  lots.     The  contractor  shall  return  to  the  railway  station  at 

all  empty  sacks  securely  bound  in  bundles  in  such  a  manner  and  of 

such  sizes  as  the  engineer  may  direct.     For  all  sacks  not  returned  in  serviceable 

condition  he  will  be  charged  the  same  amount  that  the  sacks  cost 

The  contractor  shall  provide  suitable  warehouses  for  storing  the  cement  and  he  will 

be  charged  at  the  same  price  that  it  cost for  all  cement  wasted  and 

damaged  after  delivery  to  him,  and  also  for  all  unused  cement  not  returned. 

176.  Sand. — Sand  for  concrete  shall  be  obtained  from  natural  deposits.     The 
particles  shall  be  hard,  durable,  non-organic  rock  fragments,  such  as  will  pass  a 
j-inch  mesh  screen.     The  sand  must  be  free  from  organic  matter  and  must  contain 
not  more  than  10  per  cent  of  clayey  material.     The  sand  must  be  so  graded  that, 
when  dry  and  well  shaken  its  voids  will  not  exceed  35  per  cent. 

177.  Gravel. — Gravel  for  concrete  shall  consist  of  hard,  durable  rock  pebbles 

that  will  pass  through  a inch  mesh  screen  and  that  will  be  rejected  by  a 

j-inch  mesh  screen. 

178.  Water. — The  water  used  in  mixing  concrete  shall  be  reasonably  clean,  and 
free  from  objectionable  quantities  of  organic  matter,  alkali  salts  and  other  im- 
purities. 

179.  Mixing. — The  cement,  sand  and  gravel  shall  be  so  mixed  and  the  quan- 
tities of  water  added  shall  be  such  as  to  produce  a  homogeneous  mass  of  uniform 
consistency.     Dirt    and    other   foreign    substances   shall   be   carefully   excluded. 
Machine  mixing  will  be  required,  and  the  machine  and  its  operation  shall  be  sub- 
ject to  the  approval  of  the  engineer.     Enough  water  shall  be  used  to  give  the  con- 
crete a  mushy  consistency.     If  concrete  is  mixed  in  freezing  weather  the  sand  and 
gravel  or  water  shall  be  heated  sufficiently  before  mixing  to  remove  all  frost. 

180.  Placing. — No  concrete  shall  be  used  that  has  attained  its  initial  set.  and 


576  SPECIFICATIONS 

such  concrete  shall  be  immediately  removed  from  the  site  of  the  work.     No  con- 
crete shall  be  placed  except  in  the  presence  of  a  duly  authorized  inspector. 

181.  Hauling. — In  handling  and  hauling  the  sections  of  pipe  great  care  shall  be 
taken  to  avoid  injury  to  the  pipe  and  suitable  cradles  shall  be  provided  to  avoid 
concentration  of  the  entire  weight  on  small  areas.     The  sections  of  pipe  shall  be 
distributed  along  the  trench  as  directed  by  the  engineer.     Any  pipes  that  are 
seriously  injured  in  handling  or  hauling  will  be  rejected  and  shall  be  immediately 
removed  from  the  site  of  the  work  or  demolished  and  the  contractor  shall  replace 
the  same  with  other  sections  of  pipe  having  the  same  quantitiy  of  reinforcement. 

182.  Laying. — The  sections  of  pipe  shall  laid  be  true  to  line  and  grade  accord- 
ing to  stakes  established  by  the  engineer   and  with  only  sufficient  joint  space 
between  to  allow  for  satisfactory  caulking.     Before  making  the  joints  the  adjacent 
sections  of  pipe  shall  be  firmly  bedded  or  supported  by  blocks  to  prevent  the 
slightest  movement  while  the  joint  is  being  made. 

183.  Joints. — Joints  may   be   made  by   sectional   collars  separately  moulded 
and  set  in  grooves  in  the  ends  of  the  pipe  sections,  or  by  pouring  concrete  on  the 
outside  of  the  pipe  into  suitable  flexible  forms  and  at  the  same  time  pointing  and 
smoothing  off  on  the  inside  with  a  i  to  i  mixture  of  mortar.     The  concrete  used 
for  joints  shall  be  equal  to  or  better  in  quality  than  that  used  for  the  pipe.     Each 

joint  shall  be  reinforced  with steel  rods,  or  the  equivalent  in  area  of 

some  other  form  of  reinforcement  satisfactory  to  the  engineer.     As  soon  as  the  joint 
has  been  made  it  shall  be  covered  with  wet  cloths  and  kept  so  covered  for  ten 
days  thereafter.     If  desired,  after  the  concrete  has  attained  its  final  set,  damp 
earth  may  be  substituted  for  the  wet  cloths. 

184.  Tests  of  Pipe. — On  completion  of  the  work,  or  as  soon  as  possible  there- 
after, the  contractor  shall  make  a  full  pressure  test  of  the  pipe,  water  being  furnished 

therefore  by All  leaks  found  at  the  time  of  the  test  shall  be  made 

tight  by  the  contractor.     The  cost  of  making  the  test,  except  furnishing  water, 
shall  be  borne  by  the  contractor. 

185.  Measurement. — The  price  bid  per  linear  foot  shall  be  for  pipe  complete 
in  place,  ready  for  service,  and  shall  include  all  material,  except  cement,  entering 
into  or  used  on  the  work,  manufacture,  hauling,  laying,  jointing,  testing,  repairing 
leaks,  etc.,  until  final  inspection  and  acceptance  by  the  engineer.     The  number 
of  linear  feet  of  pipe  in  place  will  be  measured  along  the  axis  of  the  pipe  after 
completion. 

1 86.  Payments. — At  the  end  of  each  calendar  month  60  per  cent  of  the  contract 
price  for  pipe  in  place  shall  be  paid  to  the  contractor  for  all  pipe  manufactured 
during  that  month;   30  per  cent  additional  shall  be  paid  for  pipe  laid  and  jointed; 
and  the  remainder  shall  be  paid  after  final  test  and  acceptance  of  the  pipe  by  the 
engineer,  and  when  the  terms  of  the  contract  shall  have  been  fully  complied  with 

to  the  satisfaction  of  the  engineer,  and  a  release  of  all  claims  against 

,  under,  or  by  virtue  of  the  contract,  shall  have  been  executed  by  the  con- 
tractor. 

METAL  FLUMES 

187.  Type  of  Flume. — All  flumes  furnished  under  these  specifications  shall  be 
made  of  metal  and  shall  be  of   the  semicircular,  smooth-interior  type.     Bidders 


SPECIAL  REQUIREMENTS  577 

shall  submit  with  their  proposals  a  drawing  or  catalogue  cut  showing  clearly  the 
type  of  construction  and  detailed  dimensions  of  the  flume  that  they  propose  to 
furnish.  Smoothness  of  interior  surface  and  ease  of  erection  will  be  important 
factors  in  the  consideration  of  proposals. 

1 88.  Dimensions  and  Weight  of  Flume. — The  assembled  flume  shall  have  an 

interior  diameter  of feet inches  and  the  depth  shall  be  that  of  the 

full  semicircle.     The  bidder  shall  state  the  weight  of  the  completed    flume  per 
linear  foot.     A  complete  flume  shall  consist  of  sheets  carrier  rods,  compression 
bars,  shoes,  nuts  and  washers. 

189.  Thickness  of  Metal  Sheets. — The  thickness  of  the  metal  sheets  shall  be 
sufficient  to  provide  necessary  rigidity  and  stiffness.     The  following  minimum 
thicknesses  shall  be  used: 

No.  of  Flume.  U.  S.  Standard  Gage. 

24  to  108 20 

120  to  156 18 

168  to  204 16 

216  and  larger 14 

For  the  larger  sizes  of  flumes  intermediate  carrier  rods  or  reinforcing  ribs  shall  be 
furnished,  if  necessary,  to  maintain  the  true  semicircular  shape  of  the  sheets  when 
subjected  to  the  full  weight  of  water. 

190.  Size  of  Carrier  Rods  and  Compression  Bars. — Carrier  rods  shall  be  designed 
for  a  working  stress  of  8000  pounds  per  square  inch  when  subjected  to  the  full 
weight  of  the  water;    provided  that  the  smallest  allowable  carrier  rod  shall  be 
|-inch  in  diameter  or  its  equivalent.     Carrier  rods  shall  be  threaded  at  both 
ends  and  provided  with  nuts  and  washers.     They  shall  be  stronger  in  thread  than 
in  body.     Compression  bars  shall  be  equivalent  to  or  larger  in  cross-section  than 
the  corresponding  carrier  rods.     Compression  bars  shall  be  provided  with  shoes  for 
distributing  the  pressures  on  supporting  timbers.     The  size  and  shape  of  shoes 
and  washers  shall  be  such  as  to  properly  distribute  the  pressures  on  the  wooden 
timbers  supporting  the  flume,  and  the  average  pressure  on  the  timbers  due  to  the 
full  weight  of  the  water  in  the  flume  shall  not  exceed  400  pounds  per  square  inch. 
All  carrier  rods,  compression  bars,  shoes,  nuts  and  washers  shall  be  coated  before 
shipment  by  being  dipped  when  hot  in  a  mixture  of  pure  California  asphalt,  or  its 
equivalent;   not  less  than  7  per  cent  nor  more  than  10  per  cent  of  pure  linseed  oil 
shall  be  mixed  with  the  asphalt.     Materials  for  coating  shall  be  subject  to  the 
approval  of  the  engineer. 

191.  Joints. — The  joints  between  successive  sheets  comprising  the  flume  lining 
shall  be  designed  to  be  rigid  and  water  tight  and  shall  offer  the  -least  possible 
obstruction  to  the  flow  of  water  through  the  flume.     All  necessary  crimping  of 
sheets  to  form  the  joints  shall  be  done  by  the  contractor. 

192.  Curves. — The  metal  sheets  for  curved  flumes  shall  be  fabricated  so  as  to 
conform  exactly  to  the  degree  of  curvature  required.     The  engineer  will  furnish 
the  contractor  a  list  of  lengths  of  flumes  required  of  each  degree  of  curvature  and 
the  degree  of  curvature  shall  be  plainly  stamped  on  each  sheet. 

193.  Materials  for  Sheets. — The  metal  sheets  shall  be  manufactured  from  steel 
and  shall  be  galvanized.     The  chemical  and  physical  properties  shall  be  as  follows: 


578  SPECIFICATIONS 

Elements  Considered.                  Open-hearth  Steel.  Bessemer  Steel. 

Carbon  max.  per  cent 0.07-0.14  0.07-0.14 

Manganese,  per  cent o .  34-0 .46  i .  oo 

Phosphorus,  per  cent .03  .10 

Sulphur,  per  cent .05  .07 

Silicon,  per  cent .02  .02 

Copper,  per  cent Recorded  Recorded 

Ultimate  strength 50,000-60,000  50,000-60,000 

Elastic  limit 25,000-35,000  25,000-35,000 

Minimum  elongation  in  8  inches.  25  per  cent  25  per  cent 

The  material  shall  show  homogeneity  of  structure  as  exhibited  by  the  ends  of 
the  broken  test  specimens. 

194.  Material  for  Compression  Bands  and  Carrier  Rods. — These  shall  be  made  of 
medium  steel  and  shall  have  an  ultimate  tensile  strength  of  55,000  to  65,000  pounds 
per  square  inch;    an  elastic  limit  of  not  less  than  one-half  the  ultimate  tensile 
strength;   a  minimum  per  cent  of  elongation  in  8  inches  of  1,400,000  divided  by 
the  ultimate  tensile  strength;   a  silky  fracture;   and  capability  of  being  bent  cold, 
without  fracture,  180  degrees  around  a  pin  having  a  diameter  equal  to  the  thickness 
of  the  test  piece. 

195.  Material  for  Shoes  and  Washers. — The  bearing  shoes  and  washers  for  com- 
pression bands  and  carrier  rods  may  be  made  of  either  gray  or  malleable  cast  iron. 
Gray  iron  castings  shall  conform  in  all  respects  to  the  standard  specifications  for 
such  castings  adopted  September  i,  1905,  by  the  American  Society  for  Testing 
Materials,  except  that  no  tensile  test  will  be  required.     Malleable  iron  castings 
shall  conform  to  the  standard  specifications  for  such  castings  adopted  November 
15,  1904,  by  the  American  Society  for  Testing  Materials. 

196.  Test  Pieces. — All  test  pieces  shall  be  furnished  by  the  contractor  at  his 
expense.     The  number  and  shape  of  test  specimens  for  gray  and  malleable  castings 
shall  be  as  prescribed  in  the  specifications  of  the  American  Society  for  Testing 

Materials  specified  in  paragraph hereof.     For  all  other  materials  at  least 

one  test  specimen  shall  be  taken  from  each  melt  and  where  possible  shall  be  cut 
from  the  finished  material.     Specimens  not  cut  from  finished  material  shall,  in 
so  far  as  possible,  receive  the  same  treatment  before  testing  as  the  finished  product. 
Tensile  test  pieces  shall  be  f  inch  in  diameter  and  shall  have  8  inches  of  gage  length. 

197.  Inspection  and  Tests. — All  necessary  facilities  and  assistance  for  making 
inspection  and  tests  shall  be  furnished  to  the  engineer  by  the  contractor  at  the  ex- 
pense of  the  contractor.     Physical   tests  and  chemical  analysis  will  be  made  by 

at  his  own  expense;  or  they  may  be  made  at  the  factory  by  the  con- 
tractor or  his  employees,  acting  under  the  direction  of  the  engineer  or  his  represen- 
tative; or  certified  tests  may,  at  the  option  of  the  engineer,  be  accepted  in  lieu 
of  the  above-mentioned  tests.  No  material  shall  be  shipped  until  all  tests  and 
final  inspection  have  been  made,  or  certified  tests  shall  have  been  accepted. 

198.  Galvanizing. — The  metal  sheets  shall  have  a  coating  of  tight  galvanizing. 
The  grooving  for  joints  and  bending  of  sheets  shall  be  done  in  such  a  manner  as 
to  avoid  any  injury  to  galvanizing.     All  sheets  on  \vhich  the  galvanizing  is  cracked 
or  otherwise  injured  will  be  rejected.     The  galvanizing  shall  consist  of  a  coating 
of  pure  zinc  evenly^and  uniformly  applied  in  such  a  manner  that  it  will  adhere 


SPECIAL  REQUIREMENTS  579 

firmly  to  the  surface  of  the  metal.  Each  square  foot  of  metal  sheets  shall  hold 
not  less  than  2  ounces  of  /.inc.  The  galvanizing  shall  be  of  such  quality  that  clean, 
dry  samples  of  the  galvanized  metal  shall  appear  black  and  show  no  copper-colored 
spots  when  they  are  four  times  alternately  immersed  for  one  minute  in  the  standard 
copper  sulphate  solution  and  then  immediately  washed  in  water  and  thoroughly 
dried.  The  coating  shall  fully  and  completely  cover  all  surfaces  of  the  material, 
and  shall  appear  smooth  and  polished  and  be  free  from  lumps  of  zinc. 

199.  Measurement  and  Payment. — Payment    will  be    made    on    the    basis    of 
the  actual  assembled  length  of  flume  measured  along  the  center  line  and  at  the 

prices  bid  in  the  schedule per  cent  of  the  contract  price  of  each  shipment 

will  be  paid  on  the  acceptance  of  the  material  by  the  inspector  and  receipt  by  the 

engineer  at of  the  bill  of  lading,  properly  receipted;    and  the  remainder 

shall  be  paid  when  all  the  material  covered  by  the  contract  shall  have  been  received 
at  its  destination  and  finally  inspected,  checked  and  accepted  by  the  engineer,  and 
the  terms  of  the  contract  shall  have  been  fully  complied  with  to  the  satisfaction  of 
the  engineer. 

STEEL  HIGHWAY  BRIDGES 

(        riveted        1     f    deck     1 

200.  Description.-^^  bridge  shall  be  of  the   (  pin_connected  j    \  through  } 

truss  type,  having  a  span,  center  to  center  of  end  bearings,  of feet 

inches,  and  a  clear  width  between  trusses  of feet.     The  bridge  shall  consist 

of spans. 

201.  Stress  Sheets  and  Loading. — The  bidder  shall  furnish  with  his  bid  a  stress 
sheet  showing  the  maximum  stress  to  which  members  are  to  be  subjected,  based 
on  the  following  loading: 

/  =  span  in  feet; 

w  =  weight  of  steel  per  square  foot  of  floor; 
^  =  live  load  per  square  foot  of  floor. 
Dead  load: 

u>=  not  less  than  the  actual  weight  of  steel. 
Wooden  floor  =  15  pounds  per  square  foot. 
Live  load: 

p—ioo  —  -^j  or  a  concentrated  load  of  30,000  pounds  on  two  axles'8  feet 

center  to  center  with  wheels  spaced  6  feet  center  to  center,  and 

two-thirds  of  the  load  on  one  axle,  assumed  to  occupy  a  space 

16  feet  in  the  direction  of  traffic  by  12  feet  at  right  angles  thereto. 

Impact:  for  chords  25  per  cent  of  uniform  live  load. 

for  web  and  floor,  40  per  cent  of  either  uniform  or  concentrated  live  load. 
Wind  load:  unloaded  chord,  100  pounds  per  linear  foot  of  bridge, 
loaded  chord,  200  pounds  per  linear  foot  of  bridge. 

NOTE. — Neither  wind  nor  concentrated  loads  are  assumed  to  act  simultaneously  with 
uniform  live  load. 

202.  Detail  Drawings.— The  contractor  shall  prepare  all  detail  and  shop  draw- 
ings.    Each  proposal  shall  be  accompanied,  in  addition  to  the  stress  sheets,  by  such 
general  drawings  of  members  and  details  as  will  clearly  show  the  type  of  construc- 
tion proposed  at  all  points,  and  all  items  that  are  necessary  to  enable  the  engineer 


580  SPECIFICATIONS 

to  determine  the  strength  of  all  parts  of  the  structure  and  whether,  as  a  whole 
and  in  all  its  parts,  it  complies  with  these  specifications.  As  soon  as  practicable 
after  the  award  of  the  contract  complete  detail  and  shop  drawings  shall  be  fur- 
nished to  the  engineer  by  the  contractor  and  these  shall  receive  the  approval 
of  the  engineer  before  work  is  commenced.  Working  drawings  shall  be  furnished 
in  triplicate.  The  approval  of  general  and  working  drawings  shall  not  relieve  the 
contractor  from  the  responsibility  for  any  errors  therein.  In  case  the  engineer 
requires  additional  copies  of  drawings  for  use  during  construction  or  for  record 
these  shall  be  furnished  by  the  contractor  without  charge. 

203.  Unit  Stresses. — The  following  limiting  working  stresses  in  pounds  per 
square  inch  of  net  cross-section  shall  be  used : 

Tension  on  rolled  sections 16,000 

Shear  on  rolled  sections 9,000 

Bearing  on  pins 20,000 

Shear  on  pins .  .  .• 10,000 

Bearing  on  shop  rivets 20,000 

Shear  on  shop  rivets 10,000 

Bearing  on  field  rivets 15,000 

Shear  on  field  rivets 7, 500 

Bearing  on  columns 16,000—  70 — 

R 

Bearing  on  expansion  rollers  per  linear  inch $ood 

d  =  diameter  of  roller  in  inches; 

L  =  unsupported  length  of  column  in  inches; 

R  =  least  radius  of  gyration  in  inches. 

No  compression  member  shall  have  an  unsupported  length  exceeding  1 20  times 
its  least  radius  of  gyration  for  main  members,  or  140  times  its  least  radius  of  gyra- 
tion for  laterals. 

204.  Reversed  Stresses. — Members  subject  to  reversion  of  stresses  shall  be  de- 
singed  to  resist  both  tension  and  compression  and  each  stress  shall  be  increased  by 
eight-tenths  of  the  smaller  stress  for  determining  the  sectional  area.     The  con- 
nections shall  be  designed  for  the  arithmetical  sum  of  the  stresses. 

205.  Combined  Stresses. — Members  subject  to  both  direct  and  bending  stresses 
shall  be  designed  so  that  the  greatest  unit  fibre  stress  shall  not  exceed  the  allowable 
unit  stress  for  the  member. 

206.  Net  Sections. — The  net  section  of  any  tension  flange  or  member  shall  be 
determined  by  a  plane  cutting  the  member  square  across  at  any  point.     The 
greatest  number  of  rivet  holes  that  can  be  cut  by  any  such  plane,  or  whose  centers 
come  nearer  than  2^  inches  to  said  plane,  are  to  be  deducted  from  the  cross-section 
when  computing  the  net  area. 

207.  Minimum  Sizes. — No  metal  less  than  ^  inch  in  thickness  shall  be  used 
except  for  filling  plates.     The  smallest  angles  used  shall  not  be  less  than  2\  X  2\  X  TS 
inches.     A  single  angle  shall  never  be  used  for  a  compression  member. 

208.  Connections. — All  connections  shall  be  designed  to  develop  the  full  strength 
of  the  members.     Connecting  plates  shall  be  used  for  connecting  all  members  and 
in  no  case  shall  any  two  members  be  connected  directly  by  their  flanges.     Angles 


SPECIAL  REQUIREMENTS  581 

subject  to  tensile  stress  shall  be  connected  by  both  legs,  otherwise  only  the  section 
of  the  leg  actually  connected  will  be  considered  effective. 

209.  Portal  Bracing. — Portal  bracing  shall  consist  of  straight  members  and  shall 
be  designed  to  transmit  the  full  wind  reaction  from  the  upper  lateral  system  into 
the  end  posts  and  abutments.     The  clear  head  room  below  portal  and  sway 
bracing  for  a  width  of  6  feet  on  either  side  of  center  line  shall  be  not  less  than  15  feet. 

210.  Sway  Bracing, — Sway  bracing  of  an  approved  type  shall  be  provided  at 
each  panel  point. 

211.  Lateral  Systems. — Upper  and  lower  lateral  systems  shall  be  designed    to 
resist  the  maximum  wind  pressures  from  either  direction.     The  members  shall  be 
nearly  as  practicable  in  the  plane  of  the  axes  of  the  chords. 

212.  Floor  System. — All  floor  beams  and  stringers  shall  be  rolled  or  riveted 
steel  girders.     Floor  beams  shall  be  rigidly  connected  to  the  trusses,  and  stringers 
shall  be  rigidly  connected  to  the  floor  beams  and  their  tops  shall  be  flush  with  the 
tops  of  floor  beams. 

213.  Intersection  of  Axes  of  Members. — The  axes  of  all  members  of  trusses,  and 
those  of  lateral  systems  coming  together  at  any  apex  of  a  truss  or  girder  must 
intersect  at  a  point  whenever  such  an  arrangement  is  practicable,  otherwise  all 
induced  stresses  and  bend  of  members  caused  by  the  eccentricity  must  be  provided 
for. 

214.  Batten  Plates  and  Lattice  Bars. — The  open  sides  of  compression  members 
shall  be  stayed  by  batten  plates  at  the  ends  and  by  diagonal  lattice  bars  at  inter- 
mediate points.     Batten  plates  shall  be  used  at  intermediate  points  when,  for  any 
reason,  the  latticing  is  interrupted.     Lattice  bars  shall  be  inclined  to  the  member 
not  less  than  60  degrees  for  single  latticing  not  less   than  45  degrees  for  double 
latticing. 

215.  Eyebars. — The  thickness  of  eyebars  shall  be  not  less  than  f  inch  nor  less 
than  one-seventh  the  width  of  the  bar.     Heads  of  eyebars  shall  be  formed  by 
upsetting  and  forging  and  shall  be  so  proportioned  as  to  develop  the  full  strength 
of  the  bar.     Eyebars  shall  be  prefectly  straight  at  the  time  they  are  bored,  and 
all  bars  composing  one  member  shall  be  piled,  clamped  together,  and  bored  in  one 
operation.     The  eyebars  composing  a  member  shall  be  so  arranged  that  their 
surfaces  are  not  in  contact. 

216.  Rods. — No  rod  shall  be  used  which  has  a  cross-sectional  area  less  than 
f  square  inch.     Screw-ends  shall  be  stronger  in  thread  than  in  body. 

217.  Riveting. — The  rivets  used  shall  in  general  be  f  inch  in  diameter;   smaller 
ones  being  allowable  where  made  necessary  by  the  size  of  the  member,  but  no 
rivets  smaller  than  f  inch  in  diameter  shall  be  used  in  legs  of  an  angle  iron  equal  to 
or  greater  than  3!  inches  wide.     Not  less  than  three  rivets  shall  be  used  in  any 
main  truss,  portal  or  lower  lateral  connection  or  in  any  compression'  strut  or  sway 
bracing,  portal  bracing  or  upper  lateral  system  connection.     The  pitch  of  rivets 
in  all  classes  of  work  in  the  direction  of  the  stress  shall  never  exceed  6  inches  nor 
be  less  than  three  diameters  of  the  rivet.     At  the  ends  of  compression  members 
it  shall  not  exceed  four  times  the  diameter  of  the  rivets  for  a  length  equal  to  twice 
the  width  of  the  member.     No  rivet  hole  center  shall  be  less  than  one  and  one-half 
diameters  from  the  edge  of  the  plate,  and  whenever  practicable  this  distance  is 
to  be  increased  to  two  diameters.     The  rivets  when  driven  must  completely  fill 
the  holes.     The  rivet  heads  must  be  round,  and  they  must  be  of  uniform  size 


582  SPECIFICATIONS 

for 'the  same  size  rivets  throughout  the  work;  they  must  be  neatly  made  and  con- 
centric with  the  rivets  and  must  thoroughly  pinch  the  connected  pieces  together. 
Whenever  possible  all  rivets  shall  be  machine  driven.  No  rivet  excepting  those 
in  shoe  plates  and  roller  and  bed  plates  is  to  have  a  less  diameter  than  the  thick- 
ness of  the  thickest  plate  through  which  it  passes.  The  effective  diameter  of  any 
rivet  shall  be  assumed  the  same  as  its  diameter  before  driving,  but  in  making 
deductions  for  rivet  holes  in  tension  members  the  diameter  of  the  hole  shall  be 
assumed  f  irich  larger  than  that  of  the  rivet.  The  amount  of  field  riveting  shall 
be  reduced  to  a  minimum,  and  all  details  are  to  be  made  so  that  the  field  rivets 
can  be  driven  readily.  Rivets  shall  not  be  used  in  direct  tension.  The  contractor 
will  be  held  responsible  for  the  correct  fitting  of  all  parts  upon  assembly  in  the  field, 
and,  if  necessary,  to  insure  this,  all  members  shall  be  assembled  in  the  shop,  and 
fitted  before  shipment. 

218.  Pins. — All  pins  shall  be  turned  smoothly  to  a  gage  and  shall  be  finished 
perfectly  round,  smooth  and  straight.     All  pins  up  to  and  including  3!  inches  in 
diameter  shall  fit  the  pin-holes  within  -^-0-  inch,  all  pins  over  3^  inches  in  diameter 
shall  fit  their  holes  within  -^  inch.     The  contractor  must  provide  steel-pilot  nuts 
for  all  pins  to  preserve  the  threads  while  the  pins  are  being  driven. 

219.  Camber. — All  trusses   shall  be  cambered  by  making  the  top  chord  sec- 
tion longer  than  the  corresponding  bottom  chord  section  by  -^  inch  for  each  10 
feet  of  length. 

220.  Expansion  and  Contraction. — Provision  shall  be  made  for  changes  in  length 
due  to  temperature  variations  of  at  least  f  inch  for  each  10  feet  of  span. 

221.  Roller  Ends. — Each  truss  of  more  than  60  feet  span  shall  be  provided  with 
one  roller  end.     For  spans  60  feet  and  less  a  sliding  end  may  be  used.     Rollers  shall 
be  turned  accurately  to  gage  and  must  be  finished  perfectly  round  and  to  the  cor- 
rect diameter  or  diameters  from  end  to  end.     The  tongues  and  grooves  in  plates 
and  rollers  must  fit  snugly  so  as  to  prevent  lateral  motion.     Roller  beds  must  be 
planed.     The  smallest  allowable  diameter  of  expansion  rollers  is  3!  inches. 

222.  Anchorages. — Every  span  must  be  anchored  at  each  end  to  the  pier  or 
abutment  in  such  a  manner  as  to  prevent  lateral  motion,  but  so  as  not  to  interfere 
with  the  longitudinal  motion  of  the  truss  due  to  changes  of  temperature.     The 
shoes  or  bolsters  shall  be  so  located  that  the  anchor  bolts  will  occupy  a  central 
position  in  the  slotted  holes  at  a  temperature  of  40°  F.     Bedplates  shall  be  de- 
signed to  distribute  the  load  over  a  sufficient  area  to  keep  the  pressure  on  the 
masonry  below  400  pounds  per  square  inch. 

223.  Hand  Railing. — A  suitable  latticed  hand  railing  shall  be  provided  for  each 
truss. 

224.  Shop  Painting. — Before  leaving  the  shop  all  structural  steel,  except  as 
below  specified,  shall  be  thoroughly  cleaned  of  all  loose  scales  and  rust  and  given 
one  coat  of  good  iron  ore  paint  mixed  with  pure  linseed  oil,  which  shall  be  well 
worked  into  all  joints  and  open  spaces.     All  surfaces  of  steel  that  will  come  in 
contact  with  each  other  shall  be  painted  before  being  riveted  or  bolted  together. 
Pins,  pinholes,  screw  threads  and  all  finished  surfaces  shall  not  be  painted  but 
shall  be  coated  with  white  lead  and  tallow  as  soon  as  they  are  finished. 


SPECIAL  REQUIREMENTS  583 


MATERIAL 

225.  Manufacture. — Structural  steel  shall  be  made  by  the  open-hearth  process 
and  shall  conform  in  all  respects,  not  specifically  mentioned  herein,  to  the  Standard 
Specifications  for  Structural  Steel  for  Bridges  of  the  American  Society  for  Testing 
Materials  adopted  August  25,  1913. 

226.  Physical  and  Chemical  Properties  of  Structural  Steel. — Steel  shall  contain 
not  more  than  0.05  per  cent  sulphur,  and  not  more  than  0.04  per  cent  phosphorus 
for  basic  open-hearth  nor  more  than  0.06  per  cent  phosphorus  for  acid  open-hearth. 
It  shall  have  an  ultimate  tensile  strength  of  55,000  to  65,000  pounds  per  square 
inch;   an  elastic  limit,  as  indicated  by  the  drop  of  beam  of  not  less  than  one-half 
the  ultimate  tensile  strength;    a  minimum  per  cent  of  elongation  in  8  inches  of 
1,500,000  divided  by  the  ultimate  tensile  strength;   a  silky  fracture  and  capability 
of  being  bent  cold  without  fracture  180  degrees  flat  on  itself  for  material  f  inch 
thick  and  under;  for  material  over  f  inch  to  and  including  if  inches  around  a  pin 
having  a  diameter  equal  to  the  thickness  of  the  test  piece;   and  for  material  over 
ij  inches  thick,  around  a  pin  having  a  diameter  equal  to  twice  the  thickness  of  the 
test  piece.     A  deduction  of  2.5  will  be  allowed  in  the  specified  percentage  of  elonga- 
tion for  each  ^  inch  in  thickness  below  ^  inch  and  a  deduction  of  i  will  be  allowed 
for  each  £  inch  in  thickness  above  f  inch. 

227.  Physical  and  Chemical  Properties  of  Rivet  Steel. — Rivet  steel  shall  contain 
not  more  than  0.04  per  cent,  each  of  sulphur  and  phosphorus.     It  shall  have  an 
ultimate  tensile  strength  of  45,000  to  55,000  pounds  per  square  inch;    an  elastic 
limit  as  determined  by  the  drop  of  beam  of  not  less  than  one-half  the  ultimate 
tensile  strength;  a  minimum  per  cent  of  elongation  in  8  inches  of  1,500,000  divided 
by  the  ultimate  tensile  strength;    a  silky  fracture;    and  capability  of  being  bent 
cold  without  fracture  180  degrees  flat  on  itself. 

228.  Finish. — Finished  material  must  be  free  from  injurious  seams,  flaws,  or 
cracks,  and  have  a  workmanlike  finish. 

229.  Marking. — Every  finished  piece  of  steel  shall  have  the  melt  number 
stamped  or  rolled  upon  it.     Steel  for  pins  and  rollers  shall  be  stamped  on  the  end. 
Rivet  steel  and  other  small  parts  may  be  bundled,  with  the  above  marks  on  an 
attached  metal  tag. 

230.  Test  Pieces. — (See  paragraph  40.) 

231.  Tests. — (See  paragraph  41.) 

232.  Payment  for  Fabricated  Material. — per  cent  of  the  contract  price 

of  each  shipment  will  be  paid  on  the  acceptance  of  the  material  by  the  inspector 
and  receipt  by  the  engineer  of  the  bill  of  lading,  properly  receipted  (and  the  re- 
mainder will  be  paid  when  all  of  the  material  covered  by  the  contract  shall  have 
been  received  at  its  destination  and  finally  inspected,  checked  and  accepted  by 
the  engineer,  and  the  terms  of  the  contract  shall  have  been  fully  complied  with 
to  the  satisfaction  of  the  engineer). 

(NOTE. — Portion  in  parentheses  is  to  be  omitted  here  when  erection  is  included  in  the 
contract.) 

ERECTION 

233.  Material  and  Labor. — The  contractor  shall  furnish  all  labor,  tools,  machin- 
ery and  materials,  except  wood  flooring,  for  erecting  the  bridge  complete  in  place, 


584  SPECIFICATIONS 

including  all  hauling,  erection  and  dismantling  of  all  falsework  and  staging,  setting 
of  anchor  bolts,  and  all  other  work  necessary  for  the  completion  of  the  structure 
ready  for  traffic . 

234.  Wood  Floor. — Lumber  for  flooring  will  be  furnished  by , 

but  shall  be  put  in  place  by  the  contractor  and  he  shall  furnish  all  necessary  fas- 
tenings.    The  lumber  will  be  delivered  to  the  contractor  at  the  railroad  station 
most  convenient  to  the  work  and  the  contractor  shall  haul  same  to  the  bridge  site. 

235.  Painting  after  Erection. — After  erection  all  metal  work  shall  be  thoroughly 
cleaned  of  mud,  grease  and  other  objectionable  matter  and  evenly  painted  with 
two  coats  of  paint  of  the  kind  and  colors  specified  by  the  engineer.     Linseed  oil 
shall  be  used  as  the  vehicle  in  mixing  the  paint  for  each  of  these  coats  and  the 
separate  coats  shall  have  distinctively  different  shades  of  color.     All  recesses  which 
might  retain  water  shall  be  filled  with  thick  paint  or  some  waterproof  material 
before  final  painting.     The  first  coat  shall  be  allowed  to  become  thoroughly  dry 
before  the  second  coat  is  applied.     No  painting  shall  be  done  in  wet  or  freezing 
weather. 

236.  Final  Payment. — Final  payment  will  be  made  upon  completion  of  the  erec- 
tion and  acceptance  of  the  finished  structure  by  the  engineer,  and  when  the  terms 
of  the  contract  shall  have  been  fully  complied  with  to  the  satisfaction  of  the  engi- 
neer. 

TUNNELS 

237.  Excavation. — The  tunnel,  shafts  and  adits  shall  in  all  cases  be  excavated 
in  such  manner  and  to  such  dimensions  as  will  give  suitable  room  for  the  necessary 
timbering,  lining,  ventilating,  pumping  and  draining.     The  contractor  shall  use 
every  reasonable  precaution  to  avoid  excavating  beyond  the  outside  lines  of 
permanent  timbering  and  beyond  the  outside  neat  concrete  lines  where  no  per- 
manent timbering  is  required.     All  drilling  and  blasting  shall  be  carefully  and  skill- 
fully done  so  as  not  to  shatter  the  material  outside  of  the  required  lines.     Any 
blasting  that  would  probably  injure  the  work  will  not  be  permitted  and  any  damage 
done  to  the  work  by  blasting  shall  be  repaired  by  the  contractor  at  his  expense, 
and  in  a  manner  satisfactory  to  the  engineer.     Tunnel  excavation  will  be  paid 
for  at  the  price  bid  per  linear  foot.     Partial  excavation,  as  in  the  case  of  a  heading, 
amounting  to  not  less  than  one-half  the  full  section  will  be  allowed  for  in  the 
monthly  progress  estimates  at  one-fourth  of  the  price  named  in  the  contract  for  full 
excavation. 

238.  Timbering. — Suitable  timbering  and  lagging  shall  be  used  to  support  the 
tunnel,  sides  and  roof  wherever  necessary.     If  practicable,  this  timbering  may  be 
removed  before  the  construction  of  the  concrete  lining.     Timbering  may  be  left 
in  place,  provided  it  is  constructed  in  such  a  manner  as  not  to  weaken  the  concrete 
lining  and  is  in  accordance  with  designs  approved  by  the  engineer.     An  approved 
design  for  such  permanent  timbering  is  shown  in  the  drawings  but,  in  case  this  design 
is  found  to  be  inadequate  it  may  be  modified  from  time  to  time,  subject  to  the 
approval  of  the  engineer.     Lumber  for  timbering  shall  be  furnished  by  the  con- 
tractor.    The  cost  of  furnishing  and  placing  permanent  and  temporary  timbering 
shall  be  included  in  the  price  per  linear  foot  bid  in  the  schedule  for  excavating  the 

tunnel,  except  that  in  addition  thereto  the  contractor  will  be  paid  the  sum  of 

dollars  per  M  feet  B.  M.  for  permanent  timbering  in  place.     No  payment  will 


SPECIAL  REQUIREMENTS  585 

be  made  for  temporary  timbering  nor  for  timber  used  in  filling  cavities.  In  meas- 
uring permanent  timbering  for  payment,  the  net  length  of  pieces  and  the  commer- 
cial cross-sectional  dimensions  will  be  taken.  Nothing  herein  contained  shall 
prevent  the  contractor  from  placing  such  temporary  timbering  as  he  may  deem 
necessary  nor  from  using  heavier  permanent  timbering  than  that  shown  in  the  draw- 
ings, nor  shall  be  construed  to  relieve  the  contractor  from  sole  and  full  responsi- 
bility for  the  safety  of  the  tunnel  and  for  damage  to  person  and  property. 

239.  Concrete  Lining. — The  tunnel  shall  be  lined  throughout  with  concrete. 
The  tunnel  lining  side  walls  and  arch,  where  permanent  timbering  is  not  required, 

shall  have  an  average  thickness  of inches,  with  a  minimum  thickness  of 

inches  over  projecting  points  of  rock.     The  average  thickness  of  the  con- 
crete tunnel  invert  shall  be inches.     Where  permanent  timber  is  required 

it  shall  be  set  back  so  far  that  the  concrete  lining  will  cover  the  timber  at  least 
inches.     The  concrete  for  such  timber  portions  of  the  tunnel  will  be  esti- 
mated as  having  an  average  thickness  of inches.     If  the  tunnel  is  excavated 

to  greater  dimensions  than  necessary  for  placing  the  prescribed  average  thickness 
of  the  concrete  lining,  the  excess  space  shall  be  solidly  rilled  with  concrete,  or  the 
lining  shall  be  confined  with  forms  to  the  prescribed  thickness  and  properly  back- 
filled.    Concrete  tunnel  lining  will  be  paid  for  by  the  cubic  yard  at  the  unit  price 
named  in  the  contract,  measured  to  the  neat  lines  shown  in  the  drawings,  based 
on  the  average  thickness  herein  specified. 

240.  Lines  and  Grades. — The  contractor  shall  provide  such  forms,  spikes,  nails, 
troughs  for  plumb-bob  lines,  light,  etc.,  and  such  assistance  as  may  be  required 
by  the  engineer  in  giving  lines  and  grades,  and  the  engineer's  marks  shall  be  care- 
fully preserved.     Work  in  the  shafts,  adits  and  tunnel  shall  be  suspended  for  such 
reasonable  time  as  the  engineer  may  require  to  transfer  lines  and  to  mark  points 
for  line  and  grade.     No  allowance  will  be  made  to  the  contractor  for  loss  of  time 
on  account  of  such  suspension. 

241.  Draining. — The  contractor  shall  drain  the  tunnels  and  adits  where  neces- 
sary to  rid  the  same  of  standing  water.     Pumping  shall  be  done  where  gravity 
flow  to  an  outlet  can  not  be  secured.  i 

242.  Lighting  and  Ventilating. — The  contractor  shall  properly  light  and  venti- 
late the  tunnel  during  construction. 

243.  Storage  and  Care  of  Explosives. — Caps  or  other  exploders  or  fuses  shall  in 
no  case  be  stored  or  kept  in  the  same  place  in  which  dynamite  or  other  explosives 
are  stored.     The  location  and  design  of  powder  magazines,  methods  of  transport- 
ing explosives  and  in  general  the  precautions  taken  to  prevent  accidents  must  be 
satisfactory  to  the  engineer;   but  the  contractor  shall  be  liable  for  all  damages  to 
person  or  property  caused  by  blasts  or  explosions. 

244.  Backfilling. — Any  space  outside  of  the  concrete  tunnel  lining  shall  be  com- 
pactly refilled  at  the  expense  of  the  contractor  with  such  of  the  excavated  material 
from  the  tunnel  as  may  be  approved  by  the  engineer.     Large  cavities  in  the  tunnel 
roof  may  be  filled  with  waste  timber.     The  backfilling  to  the  springing  lines  of 
the  arch  shall  be  placed  before  the  arch  is  constructed,  and  shall  be  brought  up 
evenly  on  both  sides  of  the  tunnel;  it  shall  be  spread  in  layers  not  exceeding  6 
inches  in  thickness  and  well  rammed.     The  invert  and  side  walls  shall  be  braced,  if 
required,  during  the  placing  of  the  back-filling. 

245.  Adits  and  Shafts. — The  contractor  shall  construct  at  his  own  expense  such 


586  SPECIFICATIONS 

adits  and  shafts  as  he  may  desire  to  use  to  expedite  the  tunnel  work.  The  sides 
and  the  arch  of  the  tunnel  lining  situated  immediately  beneath  the  opening  of  each 
shaft  shall  be  increased  to  such  suitable  thicknesses  as  the  engineer  may  prescribe; 
and  each  adit  shall  be  closed  at  the  point  where  it  meets  the  tunnel  with  a  block  of 
concrete  averaging  at  least  4  feet  in  thickness,  extending  into  the  sides  of  the  adit 
2  feet  and  having  a  foundation  2  feet  below  the  bottom  of  the  tunnel.  All  concrete 
required  for  this  purpose  shall  be  furnished  by  the  contractor  at  his  own  expense, 
the  cement  for  which  will  be  furnished  to  the  contractor  at  its  cost  on  the  work. 
All  shafts  must  be  compactly  refilled.  Dumping  from  the  top  will  not  be  allowed 
until  the  tunnel  arch  has  been  covered  to  a  depth  of  at  least  10  feet.  After  the 
completion  of  the  block  of  concrete  required  for  closing  an  adit  the  adit  shall  be 
refilled  and  the  filling  tamped  into  place  for  a  distance  of  20  feet  from  the  tunnel. 

TELEPHONE  SYSTEM 

NOTE. — For  short  telephone  lines  serving  a  small  number  of  stations  a  ground  return 
circuit  will  in  general  give  satisfactory  service.  For  long  lines  or  those  having  many  sta- 
tions a  metallic  circuit  will  be  preferable.  In  determining  whether  to  use  the  ground  circuit 
or  metallic  circuit  the  engineer  should  carefully  study  the  importance  of  continuity  of  ser- 
vice, the  length  of  line  and  number  of  stations,  the  liability  of  disturbance  by  existing  or 
contemplated  electrical  systems  and  other  local  conditions.  For  the  usual  telephone 
systems  No.  12  wire  will  be  amply  large,  but  for  lines  subjected  to  exceptionally  heavy  loads 
of  sleet  and  snow  the  use  of  No.  10  wire  may  be  necessary. 

246.  Pole  Line. — The  pole  line  will  follow  tangents  and  curves  as  shown  in  the 
drawings  and  will  have  the  number  of  corners  therein  shown.     An  average    of 
thirty  poles  per  mile  shall  be  used  on  tangents.     The  spans  adjoining  a  pole  on  a 
curve  at  a  corner  shall  not  exceed  150  feet  each  for  a  pull  of  5  feet,  and  the  allow- 
able length  span  shall  decrease  10  feet  for  each  increase  of  5  feet  in  the  pull  up  to 
and  including  a  pull  of  30  feet.     When  a  bend  made  on  a  single  pole  produces  a 
pull  of  more  than  30  feet  the  pole  shall  be  thoroughly  braced  or  guyed  and   the 
adjoining  spans  shall  not  exceed  100  feet  each,  or  such  a  bend  shall  be  made  on 
two  poles  and  the  lengths  of  the  adjoining  spans  adjusted  with  the  foregoing  pro- 
visions relating  to  span  and  pull.     The  term  "  pull  "  as  herein  used  means  the  per- 
pendicular distance  from  the  pole  under  consideration  to  a  straight  line  joining  the 
two  adjacent  poles.     When  a  span  of  from  200  to  250  feet  is  necessary,  the  adjoin- 
ing spans  shall  not  exceed  100  feet  each,  and  where  a  span  of  from  250  to  500  feet 
is  necessary,  the  adjoining  two  spans  at  each  end  shall  not  exceed  100  feet  each. 
On  uneven  ground  the  spans  shall  be  so  chosen  and  the  poles  so  set  as  to  avoid 
abrupt  changes  in  the  direction  of  the  wire  line  vertically.     In  distributing  poles, 
the  heaviest  shall  be  placed  so  far  as  practicable  on  corners  and  at  the  ends  of 
long  spans. 

247.  Poles. — Telephone  poles  shall  be  in  general  5-inch  poles  25  feet  in  length. 
At  crossings  of  highways,  railroads  and  gullies  6-inch  poles  of  requisite  length  shall 

be  used,  and  for  this  purpose poles  30  feet  in  length  and poles  35 

feet  in  length  will  be  required.     The  poles  shall  be  cut  from  growing  trees,  shall  be 
reasonably  well  proportioned  for  their  length  and  shall  be  peeled,  neatly  trimmed, 
well  seasoned,  reasonably  sound  and  free  from  unsightly  wind  twists,  injurious 
butt  rot  and  other  defects  that  materially  impair  them  for  the  use  intended. 
Butt  rot  in  the  center,  including  small  ring  rot  outside  of  the  center,  the  total  of 


SPECIAL  REQUIREMENTS  587 

which  does  not  exceed  10  per  cent  of  the  area  of  the  butt,  will  be  permitted.  Sweeps 
not  exceeding  i  inch  for  every  5  feet  in  length  of  pole  will  be  permitted.  The 
tops  of  seasoned  5 -inch  poles  shall  measure  not  less  than  15  inches  in  circumfer- 
ence and  those  of  6-inch  poles  not  less  than  18  inches.  If  the  poles  are  measured 
when  green  5 -inch  poles  shall  be  not  less  than  16  inches  in  circumference  at  the 
tops  and  6-inch  poles  not  less  than  19^  inches.  The  top  of  each  pole  shall  be 
trimmed  so  as  to  form  a  right-angled  roof.  The  roofs  of  poles  shall  be  painted 
with  two  coats  of  good  quality  of  iron  oxid  paint. 

248.  Setting  Poles. — On  tangents  the  poles  shall  be  set  in  a  vertical  position, 
and  on  curves  and  at  corners  they  shall  be  raked  10  inches  for  a  pull  less  than  5 
feet,  15  inches  for  a  pull  of  from  5  to  10  feet  and  25  inches  for  a  pull  of  more  than 
10  feet.     Each  pole  hole  in  earth  shall  be  5  feet  in  depth  and  shall  be  dug  of  suf- 
ficient size  throughout  to  admit  of  tamping  around  the  entire  perimeter  of  the  pole. 
On  hillsides  the  depth  of  the  holes  shall  be  measured  from  the  lowest  side  of  the 
opening.     Where  the  line  crosses  solid  rock,  pole  holes  shall  be  blasted  to  a  depth 
of  3  feet,  unless  such  solid  rock  can  be  covered  by  a  single  span  not  exceeding  250 
feet.     Each  pole  shall  be  carefully  held  in  proper  position  while  the  hole  is  being 
filled.     Filling  holes  with  earth  shall  be  done  by  one  man  and  the  earth  firmly 
tamped  simultaneously  by  three  men.     Rock  debris  when  used  for  filling  holes  shall 
contain  sufficient  earth  to  fill  all  cavities  therein  and  shall  be  homogeoneously 
placed  and  thoroughly  compacted.     When  the  hole  is  filled,  earth  or  rock  shall  be 
piled  and  firmly  packed  about  the  hole  to  a  height  of  i  foot  above  the  original 
ground  surface.     The  filling  for  holes  and  the  general  manner  of  setting  poles  shall 
be  such  as  will  enable  each  pole  to  withstand  the  strains  to  which  it  will  be  sub- 
jected. 

249.  Braces. — Braces  shall  be  5  inches  in  diameter  at  the  top,  shall  be  long 
enough  to  attach  to  the  pole  at  two-thirds  the  height  thereof  above  the  ground, 
to  make  an  angle  of  30  degrees  therewith  and  to  extend  into  the  ground  at  least 
4  feet  measured  along  the  brace  and  shall  conform  in  all  other  respects  to  the 

specifications  for  poles braces feet  in  length, braces 

feet  in  length  and braces feet  in  length  will  be  required. 

250.  Setting  Braces. — Each  brace  shall  be  set  in  the  ground  at  least  3!  feet  in 
vertical  depth.     The  brace  shall  be  cut  slanting  at  the  top  to  fit  close  to  the  pole 
and  shall  be  attached  to  the  pole  with  a  f-inch  bolt  supplied  with  a  washer  at  each 
end.    This  bolt  shall  be  placed  at  the  lowest  point  of  the  joint.     In  fitting  the  brace 
to  the  pole  all  trimming  shall  be  done  on  the  brace. 

251.  Guys   and  Anchors.— Guys  shall  consist  of  No.  6,  B.W.G.,  galvanized 

steel  wire.     Guy  anchors  in  earth  shall  consist  of and  galvanized  iron  rods. 

(If  cast-iron  anchor  plates  are  used  they  shall  be  8  inches  square  and  \  inch  thick 
and  shall  be  provided  on  the  lower  face  with  a  cylindrical  lug  at  the  center  having 
a  diameter  of  2  inches,  and  a  height  of  i^  inches  and  with  diagonal  ribs  \  inch 
thick  rising  from  zero  elevation  at  the  corners  and  terminating  in  the  cylindrical 
lug  with  elevation  equal  thereto.     Each  cast-iron  plate  shall  have  a  f-inch  cored 
hole  through  its  center  for  the  reception  of  the  anchor  rod.)     Each  galvanized 
iron  rod  shall  be  f  inch  in  diameter  and  6  feet  in  length  and  shall  be  provided  at 
the  upper  end  with  a  suitable  eye  and  a  wire  rope  thimble  for  a  J-inch  rope  and  at 
the  lower  end  with  U.  S.  standard  threads  and  a  galvanized  iron  nut.     Guy  anchors 
in  rock  shall  consist  of  galvanized  iron  rods  of  the  combination  eye  and  wedge-bolt 


588  SPECIFICATIONS 

type  i  inch  in  diameter  and  18  inches  in  length,  each  provided  with  a  suitable 
wedge  and  a  wire  rope  thimble  for  a  j-inch  rope. 

252.  Placing  Gtiys  and  Anchors. — Each  guy  shall  be  attached  to  tb~  pole  imme- 
diately below  the  bracket  by  making  two  turns  around  the  pole  and  wrapping 
the  end  eight  times  around  the  guy  and  shall  be  secured  to  its  rod  by  passing  around 
the  thimble  and  terminating  on  itself  in  eight  turns.     The  turns  about  the  pole 
shall  be  secured  by  at  least  three  2-inch  galvanized  iron  staples.     The  angle  between 
the  guy  and  its  pole  shall  be  as  nearly  45  degrees  as  is  practicable. 

253.  Guying  and  Bracing. — Guys  and  braces  shall  be  placed  wherever  considered 
essential  by  the  engineer.     On  tangents  and  on  curves  having  pulls  less  than  10 
feet  double  side  guys  will  be  required  about  every  1000  feet  of  line;  and  on  curves 
or  at  corners  where  the  pull  is  from  10  to  30  feet  each  pole  shall  be  provided  with  a 
guy  or  brace.     On  curves  and  at  corners  each  pole  at  which  the  pull  exceeds  30 
feet  shall  be  provided  with  either  a  guy  or  a  brace  placed  in  the  plane  of  each 
of  the  adjoining  spans  and  the  adjacent  poles  shall  be  provided  with  appropriate 
supplemental  bracing  or  guying.     At  least  one  head  and  one  back  guy  shall  be 
installed  on  every  mile  of  line.     Additional  head  and  back  guys  or  braces  shall  be 
used  wherever  the  slope  of  the  ground,  length  of  span,  change  in  direction  or  extra 
pole  height  at  road  crossings  requires  them  for  stability. 

254.  Brackets  (Ground  Circuit). — Pony  telephone  side  brackets  15X2X10  inches 
shall  be  used.     They  shall  be  made  of  the  best  quality  of  well-seasoned,  sound, 
straight-grained  oak,  free  from  knots  and  sapwood,  shall  have  the  insulator  threads 
truly  cut  and  complete  and  shall  be  painted  with  two  coats  of  the  best  quality  of 
iron  oxid  paint.     Each  bracket  shall  be  securely  fastened  to  the  pole  with  one 
4od  and  one  6od  galvanized  wire  nail  in  such  a  position  that  the  base  of  the  bracket 
will  be  about  14  inches  below  the  top  of  the  pole.     Where  the  change  in  direction 
of  the  wire  at  any  pole  is  more  than  60  degrees  an  extra  bracket  shall  be  used. 
Brackets  shall  be  placed  on  the  same  side  of  all  poles  except  on  curves  or  at  corners, 
where  they  shall  be  so  placed  that  the  strains  produced  by  the  wires  will  tend  to 
press  the  insulators  toward  the  poles. 

255.  Brackets    (Metallic   Circuit). — Pony   telephone  side  brackets    1^X2X10 
inches  shall  be  used.     They  shall  be  made  of  the  best  quality  of  well-seasoned, 
sound,  straight-grained  oak,  free  from  knots  and  sapwood,  shall  have  the  insulator 
threads  truly  cut  and  complete  and  shall  be  painted  with  two  coats  of  the  best 
quality  of  iron  oxid  paint.     Each  bracket  shall  be  securely  fastened  to  the  pole 
with  one  40^  and  one  6od  galvanized  wire  nail.     Where  the  change  in  direction  of 
the  wire  at  any  pole  is  more  than  60  degrees  an  extra  bracket  shall  be  used  for  each 
wire.     On  tangents  the  brackets  shall  be  placed  one  on  each  side  of  the  pole  and 
on  curves  and  corners  they  shall  be  so  placed  that  the  strains  produced  by  the 
wires  will  tend  to  press  the  insulators  toward  the  poles.     The  top  bracket  shall  be 
so  placed  that  its  base  will  be  about  14  inches  below  the  top  of  the  pole,  and  the 
bottom  bracket  so  that  its  base  will  be  12  inches  below  that  of  the  top  bracket, 
except  on  transposition  poles  on  tangents.     On  transposition  poles  the  brackets 
shall  be  at  the  same  elevation  so  placed  that  the  insulator  for  each  wire  will  be  as 
nearly  as  practicable  on  a  straight  line  between  those  for  the  same  wire  on  the 
adjacent  poles. 

256.  Insulators  (Ground  Circuit). — Standard  pony,  glass,   lo-ounce  insulators 
shall  be  used.     They  shall  be  made  of  common  glass,  shall  be  free  from  cracks. 


SPECIAL  REQUIREMENTS  589 

blow-holes,  flaws  and  sharp  edges  and  shall  have  smooth  threads  of  uniform  pitch 
accurately  fitting  the  threads  on  the  brackets. 

257.  Insulators  (Metallic  Circuit}. — Standard  pony,  glass,  lo-ounce  insulators 
and  two-piece  transposition  insulators  of  equivalent  strength  shall  be  used.     They 
shall  be  made  of  common  glass,  shall  be  free  from  cracks,  blow-holes,  flaws  and  sharp 
edges  and  shall  have  smooth  threads  of  uniform  pitch  accurately  fitting  the  threads 
on  the  brackets. 

258.  Line  Wire. — The  line  wire  shall  consist  of  No.  12,  B.W.G.,  galvanized 
iron  wire  of  the  quality  known  as  "  Best  Best,"  having  an  average  resistance  at 
68°  F.  not  to  exceed  34-4-  ohms  per  mile.     The  wire  shall  be  of  uniform  cross-section, 
shall  weigh  approximately  170  pounds  per  mile,  shall  have  an  ultimate  tensile 
strength  of  not  less  than  560  pounds  and  shall  be  capable  of  withstanding  at  least 
fifteen  twists  about  its  axis  in  a  length  of  6  inches.     It  shall  be  soft  and  pliable 
and  capable  of  elongating  15  per  cent  without  breaking,  after  being  galvanized. 
The  diameter  of  the  line  wire  in  inches  shall  be  not  more  than  0.113  nor  less  than 
o.i 06.     The  wire  shall  be  furnished  in  coils  of  \  mile  or  i  mile  continuous  lengths, 
without  welds,  joints  or  splices,  and  each  coil  shall  be  drawn  from  a  rod  without 
welds,  joints  or  splices  of  any  kind.     The  galvanizing  shall  consist  of  a  coating 
of  pure  zinc  evenly  and  uniformly  applied  in  such  a  manner  that  it  will  adhere 
firmly  to  the  surface  of  the  metal.     The  galvanizing  shall  be  of  such  quality  that 
clean  dry  samples  of  the  galvanized  wire  shall  appear  black  and  show  no  copper- 
colored  spots  after  they  have  been  four  times  alternately  immersed  for  one  minute 
in  the  standard  copper  sulphate  solution  and  then  immediately  washed  in  water 
and  thoroughly  dried. 

259.  Stringing  Wire. — The  wire  shall  be  strung  with  as  few  joints  as  possible 
and  shall  be  joined  by  twisting  the  wires  for  a  distance  of  about  3  inches  around 
each  other  two  complete  turns  and  soldering,  the  end  of  each  wire  terminating  in 
five  tightly  fitting  contiguous  turns  around  the  other  wire.     The  line  wire  shall  be 
tied  to  the  insulators  with  tie  wires  of  No.  12,  B.W.G.,  galvanized  iron  wire  cut 
in  suitable  lengths.     The  line  wire  shall  first  be  laid  in  the  groove  of  the  insulator 
on  the  side  away  from  the  pole,  after  which  the  tie  wire  shall  be  passed  entirely 
around  the  insulator  and  line  wire  and  terminate  at  each  end  in  five  tightly  fitting 
turns  around  the  line  wire.     The  tension  on  the  line  wire  for  each  span  shall  be, 
in  the  judgment  of  the  engineer,  as  high  as  will  be  safe  for  the  minimum  tempera- 
ture for  the  locality. 

260.  Transposition  (Metallic  Circuit}. — In  general  a  transposition  of  the  line 
wires  shall  be  made  once  in  each  mile,  but  the  exact  number  and  location  of  trans- 
positions shall  conform  to  the  local  requirements  therefor.     Each  transposition  shall 
be  made  without  the  use  of  transposition  insulators  by  interchanging  the  wires 
laterally  in  one  span  and  vertically  in  the  two  succeeding  spans. 

261.  Trimming  Trees. — All  trees  along  the  line  of  such  character  and  location 
as  to  render  them  liable  to  being  blown  over  so  as  to  interfere  with  the  telephone 
wires  shall  be  cut  down  and  removed  or  burned,  and  all  trees  close  to  the  line  that 
in  the  judgment  of  the  engineer  will  not  endanger  the  telephone  wires  shall  be 
so  trimmed  as  to  leave  a  clear  space  of  10  feet  about  the  telephone  wires  in  all 
directions  under  stress  of  the  heaviest  probable  wind  storms. 

262.  Lightning  Rods. — Lightning  rods  consisting  of  No.  12,  B.W.G.,  galvanized 
iron  wire  shall  be  installed  throughout  the  line  at  intervals  of  about  \  mile.     Each 


590  SPECIFICATIONS 

rod  shall  be  located  about  one-fourth  the  distance  around  the  pole  from  the  bracket 
and  shall  be  attached  to  the  pole  with  2-inch  galvanized  iron  staples.  The  upper 
end  of  each  rod  shall  project  about  3  inches  above  the  top  of  the  pole  and  the  lower 
end  shall  terminate  beneath  the  butt  of  the  pole  in  a  flat  coil  containing  about 
6  feet  of  wire. 

263.  Lightning  Arresters. — A  lightning  arrester  shall  be  installed  on  each  line 
pole  at  which  the  current  is  transferred  from  the  line  wire  to  a  station  wire.     The 
arrester  shall  be  of  the  double-pole,  lightning  and  sneak-current  type,  shall  have 
adjustable  and  removable  carbon  blocks  mounted  upon  porcelain  bases  and  shall 
have  fuses  that  will  adequately  protect  it  from  lightning  and  sneak  currents.     The 
arrester  shall  be  connected  with  No.  12,  B.W.G.,  galvanized  iron  wire  to  any  exist- 
ing water  pipe  system  nearby  or  to  a  galvanized  iron  ground  rod  \  inch  in  diameter 
and  6  feet  in  length  driven  into  permanently  moist  earth.     The  connecting  wire 
shall  be  carefully  soldered  to  the  water  pipe  or  to  the  ground  rod.     Twenty-five 
extra  sets  of  fuses  shall  be  furnished  with  each  arrester. 

264.  Station  Wiring  (Ground  Circuit). — The  current  shall  be  carried  into  build- 
ings on  No.  1 8,  B.  &  S.  G.,  rubber-insulated  copper  wire  covered  with  black  braid 
saturated  with  waterproof  compound  and  carried  on  porcelain  knobs  having  a 
diameter  of  not  less  than  i^  inches.     The  return  pole  of  each  instrument  shall  be 
connected  by  means  of  a  similar  wire  to  any  existing  water  pipe  system  nearby 
or  to  a  galvanized  iron  ground  rod  |  inch  in  diameter  and  6  feet  in  length  driven 
into  permanently  moist  earth.     The  connecting  wire  shall  be  carefully  soldered  to 
the  water  pipe  or  to  the  ground  rod.     Inside  wiring  shall  consist  of  No.  18,  B.  & 
S.  G.,  rubber-insulated  copper  wire  covered  with  braid  of  a  greenish  color.     All 
inside  wiring  shall  conform  to  the  best  practice  and  shall  be  done  only  by  expert 
electricians.     Where  wires  pass  through  walls  and  partitions  insulated  bushing 
shall  be  provided. 

265.  Station  Wiring  (Metallic  Circuit}. — The  current  shall  be  carried  into  and 
out  of  buildings  on  No.  18,  B.  &  S.  G.,  rubber-insulated  copper  wire  covered  with 
black  braid  saturated  with  weatherproof  compound  and  carried  on  porcelain  knobs 
having  a  diameter  of  not  less  than  i|  inches.     Inside  wiring  shall  consist  of  No. 
1 8,  B.  &  S.  G.,  rubber-insulated  copper  wire  covered  with  braid  of  a  greenish  color. 
All  inside  wiring  shall  conform  to  the  best  practice  and  shall  be  done  only  by  expert 
electricians.     Where  wires  pass  through  walls  and  partitions  insulated  bushings 
shall  be  provided. 

266.  Instruments. — Each  proposal  shall  be  accompanied  by  a  complete  descrip- 
tion of  the  various  essential  parts  of  the  telephone  that  the  bidder  proposes  to  fur- 
nish, which  shall  be  subject  to  the  approval  of  the  engineer. 

VITRIFIED  PIPE,  FOR  CULVERTS 

267.  Quality. — All  vitrified  pipe  shall  be  of  the  best  quality  of  smooth,  well 
burned,  salt-glazed,  vitrified  clay  sewer  pipe.     It  shall  be  of  the  hub-and-spigot 
pattern  free  from  cracks  due  to  rough  handling,  cooling,  frost  and  other  causes 
and  free  from  chippings  and  clear  fractures  that  will  impair  it  for  the  purpose  in- 
tended.    All  pipes  that  are  designed  to  be  straight  shall  not  deviate  materially 
from  a  straight  line,  and  those  designed  to  be  curved  shall  substantially  conform 
to  the  required  radius  of  curvature  and  other  general  dimensions. 


SPECIAL  REQUIREMENTS  591 

268.  Size. — Both  the  bodies  and  bells  of  all  pipes  shall  have  a  thickness  not -less 
than  one-twelfth  the  inside  diameter  of  the  pipe.     Each  hub  shall  freely  receive 
to  its  full  depth  the  spigot  end  of  the  succeeding  pipe  without  any  chipping  of  either 
and  leave  a  space  of  not  less  than  \  inch  all  around  for  the  cement  joint;   it  shall 
also  have  a  depth  from  its  face  to  the  shoulder  of  the  pipe  on  which  it  is  moulded  at 
least  2  inches  greater  than  the  thickness  of  said  pipe.     The  length  of  pipe  sections 
shall  be  between  2  and  3  feet  exclusive  of  the  socket. 

269.  Rejection. — Any  pipe  that  does  not  meet  the  above  requirements  will  be 
rejected. 


CHAPTER  XXIII 


TABLES 


TABLE  XLIIL— EXTREME  FLOOD  DISCHARGES 


, 

Maxi- 

Drain- 

mum 
Dis- 

Stream 

Locality 

age 
Area, 

charge 
in  Cu.ft. 

Date  of 
Flood 

in  Sq. 
Miles 

per  Sec. 

per  Sq. 

Mile 

I.  AMERICAN  STREAMS: 

Columbia  River  

Dalles,  Ore  

237.000 

5-9 

Ohio  River  

Paducah,  Ky  

205,750 

7  •  o 

Feb.,  1884 

Susquehanna  

Harrisburg,  Pa  

24,030 

30.6 

Mar.,  1865 

Susquehanna  

Harrisburg,  Pa  

24,030 

30. 

June,  1889 

Tennessee 

Chattanooga,  Tenn  

21,382 

34   3 

Mar,  ii,  1867 

Ohio  River 

Pittsburg,  Pa  

19,100 

22.9 

Mar.  15,  1907 

Sacramento  

Red  Bluff,  Cal  

10,400 

24.4 

Feb.,  1909 

Potomac 

Point  of  Rocks,  Md  

9,654 

48  .  9 

June  2,  1889 

Potomac  

Point  of  Rocks,  Md  

9,654 

22.6 

Mar.,  1902 

Allegheny  

Kittanning,  Pa  

9,010 

26.6 

Mar.  20,  1905 

Savannah  

Augusta,  Ga  

7,500 

40.0 

Sept.  ii,  1888 

Delaware  

Lambertville,  N.  J  

6,855 

37-  I 

Jan.  8,  1841 

Salt  

McDowell,  Ariz  

6,255 

26.1 

Monongahela  

Lock  No.  4,  Pa  

5,430 

38.1 

July  n,  1888 

Hudson  

Mechanicsville,  N.  Y  

4.500 

26.6 

Mar.  28,  1913 

Kennebec  

Waterville,  Me  

4,270 

35-3 

Dec.  16,  1901 

Neosho  

lola,  Kans  

3,670 

20.3 

July  10,  1904 

Feather  

Oroville,  Cal  

3,640 

51-3 

Mar.,  1907 

Mohawk  

Cohoes    N   Y 

3,472 

28.5 

Mar.  27,  1913 

Chattahoochee  

West  Point,  Ga  

3,300 

26.8 

Dec.  30,  1901 

Shenandoah  

Millville,  W.  Va  

2,995 

46.6 

Oct.,  1896 

Catawba  

Rock  Hil!,  S.  C  

2,987 

50.5 

May  23,  1901 

Hudson  

Glens  Falls    N.  Y. 

2,760 

25  .  3 

Mar.  28,  1913 

New  River  

Radford,  Va  

2,725 

63-3 

May,  1901 

Savannah  

Near  Calhoun  Falls,  S.  C..  . 

2,712 

27-7 

Feb.  14,  1900 

Kennebec  

Bet.  Forks  and  Waterville 

2,700 

48.  5 

Dec.  16,  1901 

Chemung  

Chemung,  N.  Y  

2,440 

21.5 

Mar.  28,  1913 

Ocmulgee. 

Macon    Ga. 

2,425 

2O  .  0 

Mar.  i,  1902 

Androscoggin  

Rumford  Falls,  Me  

2,320 

23-8 

Apr.  22,  1895 

592 


EXTREME  FLOOD  DISCHARGES 


593 


TABLE  XLIII.— EXTREME  FLOOD    DISCHARGES— Continued 


Stream 

Locality 

Drain- 
age 
Area, 
in  Sq. 
Miles 

Maxi- 
mum 
Dis- 
charge 
in  Cu.ft. 
per  Sec. 
per  Sq. 
Mile. 

Date  of 
Flood 

N.  Fork  Feather  

Big  Bend,  Cal  
Fair  Oaks  Cal 

,940 

56.3 

Mar.  19,  1907 

Near  Sanger  Cal 

74.0 

Avonmore,  Pa. 

720 

Allegheny  
San  Joaquin  
S.  Fork  Shenandoah  
Chattahoochee 

Red  House,  N.  Y  
Hamptonville,  Cal  
Near  Front  Royal,  Va.  .  .  . 
Oakdale  Ga 

,640 
,637 
,570 
560 

25.0 
36.5 
48.9 

Mar.  2,  1910 
Jan.,  1881 
Mar.,  1902 
Dec   30   1901 

Catawba 

Catawba  N.  C 

535 

61   8 

May  23    1901 

Tuolumne 

Lagrange  Cal 

500 

Jan     1911 

Cheat. 

Morgant&wn  W.  Va 

380 

30  3 

Jan.    1911 

Chagres  
Yuba  
Merced  
Scioto  
Flint  
Stanislaus  
Clarion  
Schoharie  Creek  
Schoharie  Creek  
Youghiogheny  
Passaic 

Gatun,  Panama  
Near  Smartsville,  Cal  .... 
Near  Merced  Falls,  Cal..  . 
Columbus,  Ohio  
Near  Woodbury,  Ga  
Knight's  Ferry,  Cal  
Clarion,  Pa  
Fort  Hunter,  N.  Y  
Fort  Hunter,  N.  Y  
Below  Confluence,  Pa.  ... 
Dundee  N  J 

,320 
,220 
,OQO 

,047 
988 

935 
910 
909 
900 

875 
823 

93-9 
90.9 
34-1 
80.8 
30.6 
6i.l 
43-2 
44-5 
55-1 
52.6 
38    I 

Dec.  28,  1909 
Jan.,  1909 
Jan.,  1911 
Mar.  25,  1913 
Feb.  28,  1902 
Mar.,  1907 
Mar.,  1905 
Mar.  27,  1913 
Mar.  2,  1901 
Aug.  21,  1888 

Raritan  

Bound  Brook,  N.  J  

806 

64  5 

Sept.  24,  1882 

Putah  Creek  
Hudson  
Chagres  
Broad  
Little  Tennessee  
Monocacy  
McCloud  
Hoosic  

Winters,  Cal  
North  Creek,  N.  Y  
Bohio,  Panama  
Near  Carlton,  Ga  
Judson,  N.  C  
Near  Frederick,  Md.  ..... 
Near  Gregory,  Cal  
Johnsonville,  N.  Y. 

805 
804 
779 
762 
675 
660 
608 
605 

37-2 
35-0 
II5-5 
38.2 
85.3 
31-0 
68.2 
38  o 

Mar.,  1907 
Mar.  28,  1913 
Dec.  27,  1909 
Feb.  28,  1902 
Dec.,  1901 
Mar.,  1902 
Mar.,  1904 
Mar.  28,   1913 

Stony  Creek  
Tugaloo 

Near  Fruto,  Cal  
Near  Madison  S  C 

60  1 

48.7 

36  8 

Feb.,  1909 
July  I    1905 

Santa  Catarina 

Aug   27     1909 

Coosawattee  
Cosumnes  
Clentangy  

Carters,  Ga  
Michigan  Bar,  Cal  
Columbus  Ohio 

531 

524 
514 

31  -9 

42.7 
70.0 

May  21,   1901 
Jan.,  1911 
Mar.  25,  1913 

Deerfield  
San  Luis  Rey  
Ausable  River  
Cattaraugus  Creek  
Casselman  

Shelburne  Falls,  Mass.  .  .  . 
San  Luis  Rey,  Cal  
Ausable  Forks,  N.  Y  
Versailles,  N.  Y  
Confluence  Pa 

5oi 
500 
487 
467 
448 

42.5     ' 
200.  o 
45-2 
53.5 

Apr.  15,  1909 
1916 
Mar.  27,  1913 
Mar.  25,  1913 
Mar.,  1907 

Youghiogheny  
Chagres  River  
Rio  Mora 

Confluence,  Pa  
Alhajuela,  Panama  
Weber  N.  Mex 

435 
427 

52.0 

398  .  1 
f.f   7 

Mar.,  1907 
Dec.  26,  1909 

Hiwassee  
Tygart  River  . 

Murphy,  N.  C  
Belington,  W.  Va 

410 

54-5 
40  8 

Mar.  19,  i899 

594 


TABLES 


TABLE  XLIII.— EXTREME   FLOOD    DISCHARGES— Continued 


Stream 

Locality 

Drain- 
age 
Area, 
in  Sq. 
Miles 

Maxi- 
mum 
Dis- 
charge 
in  Cu.ft. 
per  Sec. 
per  Sq. 
Mile 

Date  of 
Flood 

Pocolet 

400 

88   9 

Jennv  Lind  Cal 

395 

176   2 

Middle  Oconee 

Near  Athens  Ga 

395 

49   5 

Feb    28    1902 

Black  Lick  
Pompton  
Rondout  Creek 

Black  Lick,  Pa  
Two  Bridges,  N.  Y  
Rosendale,  N.  Y  

386 
380 
380 

50.8 
61.6 
51    3 

Mar.,  1905 
Oct.  10,  1903 
Apr    26    1910 

Esopus  Creek 

Mt.  Marion,  N.  Y  

378 

65    3 

Apr    26    1910 

W.  Canada  Creek 

Trenton  Falls,  N.  Y  

376 

96   5 

Dec    15    1901 

W.  Canada  Creek  
W.  Canada  Creek  
Piscataquis  
Bear  River  
East  Canada  Creek 

Trenton  Falls,  N.  Y  
Hinckley,  N.  Y  
Foxcroft,  Me  
Van  Trent,  Cal  
Dolgeville  N  Y 

376 
372 
286 
263 
256 

69.  i 
104.5 
77-6 
98.1 
54  3 

Mar.  28,  1913 
Apr.  21,  1869 
Sept.  29,  1909 
Mar.,  1907 

Esopus  Creek  
Toccoa 

Olivebridge,  N.  Y  
Near  Blueridge  Ga 

239 
231 

64.4 
53   o 

Apr.  26,  1910 
Aug    23    1901 

San  Gabriel  
San  Gabriel  

Near  Azusa,  Cal  
Near  Azusa,  Cal  
Near  Soledad,  Cal  

229 

222 
215 

117.0 
215  .0 
140  o 

Feb.,  1914 
1884 
Nov   21    1900 

Catskill  Creek  
Fishkill  Creek 

S.  Cairo,  N.  Y  
Glenham,  N.  Y  

2IO 
198 

IOO.O 
69    2 

Spring,  1901 
Mar.  i    1902 

Sweetwater  River  
E.  Branch  Fish  Creek  
Ramapo  River  
Rio  'Mora  
Turtle  Creek  
Devil's  Creek  
Santa  Ysabel  Creek  
E.  Branch  Fish  Creek  
Little  Stony  Creek  
Wanaque  River  
Putah  Creek  
Cedar  River  
Loramie  Reservoir  Outlet.  . 

California  
Taberg,  N.  Y  
Pompton,  N.  J  
Below  Mora,  N.  Mex  
East  Pittsburg,  Pa  
Near  Viele,  la  
Near  Escondido,  Cal  
Point  Rock,  N.  Y  
Near  Lodoga,  Cal  
Pompton,  N.  J  
Guenoc,  Cal  
Near  Seattle,  Wash  
Ohio  
Macopin,  N.  J.  

186 
169 
160 
159 
146 
143 
128 
104 

102 
101 

91 
79 

72 
62 

96.0 
65  .O 
65.8 
139-7 
64.2 
1300.0 
50.7 
80.5 
69.2 
83-6 
198.9 
I2O.O 

97-2 
90   8 

1915 
Mar.  27,  1913 
Sept.  22,  1882 
Sept.  29,  1904 
Mar.,  1904 
June  10,  1905 
Jan.,  1909 
Fall,  1897 
Feb.,  1909 
Oct.  10,  1910 
Mar.,  1904 
Nov.,  1911 
Mar.  25,  1913 
Oct.  10,  1903 

N.  Fork  Cottonwood  Creek 
Six  Mile  Creek  
Elkhorn  Creek 

Ono,  Cal  
Ithaca,  N.  Y  
Keystone,  W.  Va  

52 
46 
44 

77-7 
185.0 
1363  .0 

Feb.,  1909 
June  21,   1905 
June  22,   1901 

Basic  Creek  

Freehold,  N.  Y  

4i 
38 

81  .0 
84  o 

Spring,  1901 
Feb    6    1896 

Arroyo  Seco  
Bear  Grass  Creek  

Devil's  Gate,  Cal  
Louisville,  Ky  
Near  Bridgeport,  Conn.  .  . 

30.5 
27-5 
25  o 

352.0 
IOO.O 

157   o 

Feb.,  1914 
Feb.  22,  1908 
July  29,  1905 

Pinal  Creek 

Globe,  Ariz  

25  o 

560  o 

Aug.  17,   1904 

Bakersville,  N.  C  

22  .O 

1341  .0 

May  20,    1901 

Willow  Creek 

20    0 

1800  o 

June  14    1903 

Yuba  River 

19  o 

368 

Mill  Creek 

Erie  Pa 

12    9 

850  o 

Aug   3    1915 

EXTREME  FLOOD  DISCHARGES 


595 


TABLE  XLIIL— EXTREME   FLOOD    DISCHARGES— Continued 


Stream 

Locality 

Drain- 
age 
Area, 
in  Sq. 
Miles 

Maxi- 
mum 
Dis- 
charge 
in  Cu.ft. 
per  Sec. 
per  Sq. 
Mile 

Date  of 
Flood 

Goodyear,  Pa.  .  . 

12    2 

96  o 

Jan.  30    1911 

Mill  Brook  
Sunland  Wash  
Estanzuela  
Starch  Factory  Creek  
Rio  Grande  

Sherburne,  N.  Y  
Near  Pasedena,  Cal  
Near  Monterey,  Mex  
New  Hartford,  N.  Y  
Near  Culebra,  Panama.  .  . 
Cherryvale    Kans. 

9-4 

6-5 
3-5 
3-4 
2.3 

2    O 

241  .0 
712.0 
825.0 
151  .0 
161  .0 
930  o 

Sept.  4,  1905 
Feb.,  1914 
Aug.  28,   1909 
July  ii,  1905 
May  25,  1911 

Utica,  N.  Y.    . 

I     i 

I2O    O 

Mar   25    1904 

Beacon  Brook  

II.  EUROPEAN  STREAMS: 
Durance  River  
Allier  River  

Pishkill,  N.  Y  

Bonpas,  France  
At  junction  with  Loire, 
France 
Mirabeau    France. 

0.2 

5714 
5548 

4533 

32OO.O 

37.0 
30.0 

52  o 

July  14,  1897 

Nov.  ii,  1886 
1856 

Nov.  ii.  1886 

Allier  :  
Vistula 

Nevers,  France  
Gracow    Galicia 

4500 
3180 

37-0 
34  o 

1813 

Rhine  
Oder  

At  Lake  Constance,  Switz. 
Sagan,  Silesia,  Germany  .  . 
Galicia,  Austria. 

2555 
1638 
1420 

48.0 
43-0 
64  o 

July  31,  1897 
1897 

Eder  River 

At  junction  with  Fulda, 

1298 

35  .0 

Jan.,  1841 

Verdun  River 

Germany 
At  junction  with  Durance, 

932 

63  .0 

Nov.  i,  1843 

Glatzer  Neisse  
Ardeche  

Werre  

Eder  
Buech  

Bober 

France 
Silesia,  Germany  
At  junction  with  Rhone, 
France 
At  mouth,  Germany  

Hemfurt,  Germany  
At  junction  with  Durance, 
France 

906 
831 

575 

552 
552 

467 

47-0 
382.0 

48  .0 
32.0 
58.0 
84.0 

91.0 

1827 

Feb.,  1799 
Nov.,  1890 

Nov.  i,  1843 
July,  1897 

Hotzenplotz  
Ubaya  

At  junction  with  Oder, 
Germany 
At  junction  with  Durance, 

302 

361 

77.0 
127  .0 

July  21,  1903 
Nov.  i,  1843 

Coulon  
Bleone  
Moselle  
Asse  River. 

France 

Epinal,  France  
At  junction  with  Durance, 

352 
351 
313 

285 

IOO.O 

116.0 
90.0 
i  ii  .0 

Nov.  i,  1843 

Wupper  
Ardeche 

France 
At  mouth,  Westphalia, 
Germany 
Vans   France.                  .... 

240 
215 

90.0 
525  .6 

1890 

Bober  River  
Queis  River  

Rohrlach,  Germany  
Lauban,  Germany  

204.6 
187.4 

160.  i 
161  .  2 

July  30,  1897 
July  30,  1897 

596  TABLES 

TABLE   XLIIL— EXTREME   FLOOD   DISCHARGES— Continued 


Maxi- 

Drain- 

mum 

Dis- 

Stream 

Locality 

age 
Area, 

charge 
in  Cu.ft. 

Date  of 
Flood 

in  Sq. 

Miles 

per  Sec. 

per  Sq. 

Mile 

Ardeche  

Aubenas,  France  

178.0 

694.41 

1890 

Queis  River  

Marklissa,  Germany  

118.0 

262  .  7 

Aug.  3,  1888 

118.0 

233-3 

July  30,  1897 

Queis  River  

Greiffenberg,  Germany  .  .  . 

78.0 

172.0 

July  30,  1897 

Bargaglino  Creek  

Genoa,  Italy  

35.6 

485.0 

Oct.,  1892 

•  ' 

1  ' 

35-6 

421  .0 

July  18,  1908 

Eyach  River 

Balingen,  "Wurtemberg  . 

•2  A        7  C 

7  CfS     O 

June  5    1805 

Urnasch 

St.  Gallen,  Switzerland 

o--f  •  /  ;> 
30  o 

OOvJ  .  u 
T  r  ?     o 

Goldbach. 

At  Arnoldsdorf,  Germany 

TO     7 

1  DO  •  *J 

268.8 

July  21,  1  903 

Queis  River  

Near  Head,  Germany.  .  .  . 

*y  •  / 
12.34 

358.0 

July  31,  1897 

Little  Aupa  

Near  Head,  Germany  .... 

ii  .9 

385.63 

Furens  River  

St.  Eitenne,  France  

9.65 

478.0 

1849 

Bargaglino  Creek  

Above  Genoa,  Italy  

8.8 

732.0 

Oct.,  1892 

Eyach  River  

Margarethausen,  Wurtem- 

7-34 

788.8 

June  5,  1895 

burg 

Dabrowka  Creek  

Near  Sambor,  Austria.  .  .  . 

5-02 

253.2 

III.  INDIAN  STREAMS 

Irawaddy  

India  

149,800 

12.7 

Khrishna  

India  

345 

342.6 

Tansa. 

India. 

52 

667  .  o 

Professor  Kuichling  has  proposed  a  formula  for  maximum 
discharge  which  he  calls  especially  applicable  to  the  South 
Atlantic  States: 


Q= 


41.6(620+10 


24+M 
Fanning  gives  the  following: 


in  which  Q  =  Maximum  Discharge; 

M  =  Drainage  area  in  square  kilometers. 
Neither  of  these  formula   makes    allowance  for  differences 
in  rainfall,  grade  or  steepness  of  country,  character  of  soil  or 


EXTREME  FLOOD  DISCHARGES  597 

topography,  all  of  which,  especially  the  first,  have  great  influence 
on  the  volume  of  maximum  discharge. 

Colonel    Ryves    has    derived    the    following    formula    from 
experience  in  India: 


in  which  M  is  area  in  square  miles,  D  is  the  flood  discharge, 
and  C  is  a  coefficient  varying  with  the  rainfall  and  slope  of  the 
country.  For  regions  where  maximum  rainfalls  are  from  4  to  5 
inches  in  twenty-four  hours,  the  values  of  C  in  the  above  formula 
have  been  found  to  be  in  flat  country  C  equals  400  to  500;  in 
hilly  country  C  equals  500  to  650. 

A  formula  is  here  proposed  as  follows: 


in  which  R  equals  the  maximum  rainfall  in  inches  in  twenty- 
four  hours; 

C  varies  from  100  for  undulating  areas,  to  200  for  mountain- 
ous areas;  and 

M  equals  area  in  square  miles. 

None  of  these  formulae  can  be  expected  to  give  approximate 
results,  on  account  of  the  many  complications  involved,  and  the 
uncertainty  of  all  the  data  except  the  area  of  drainage  basin. 
The  shape  of  the  basin,  the  character  of  the  soil  and  vegetation 
and  many  minor  factors  which  affect  the  result,  are  impossible 
to  allow  for  with  any  approach  to  accuracy. 

Cost  and  Dimensions  of  Some  Great  Storage  Reservoirs.  —  In 
Table  XLIV  are  given  the  capacities,  material,  dimensions, 
purpose  and  cost  per  acre-foot  of  some  of  the  great  storage 
reservoirs  built  by  the  U.  S.  Government  for  irrigation. 


598 


TABLES 


TABLE  XLIV.— RESERVOIRS   BUILT  BY   U.   S.   RECLAMATION 

SERVICE 


Name  and  Locality 

Area, 
Acres 

Capacity, 
Acre-feet 

Annual 
Draft 

Cost 

Year 
Built 

Roosevelt,  Ariz  
East  Park  Cal. 

16,832 
i  850 

1,365,000 

5  1  ooo 

450,000 
30  ooo 

$3.883,000 

IQII 

Deerflat  Ida 

9  835 

177,660 

177,660 

Jackson  Lake,  Ida  
Minidoka,  Ida  
Arrowrock  Ida. 

25-530 
ii,350 
2,860 

789,000 
150,000 
250,000 

700,000 
53,500 
200,000 

1,253,000 
6go,ooo 

IQI5 
1906 

Pathfinder,  Wyo  
Minatare,  Neb  

22,700 
2,240 

1,070,000 
67,025 

500,000 
67,025 

1,827,000 
564,000 

1909 
1914 

Lahontan,  Xev  
MacMillan,  N.  Mex.*  
Avalon,  N.  Mex  
Elephant  Butte,  N.  M  
Cold  Springs,  Ore  
Clear  Lake,  Ore.-Cal  
Belle  Fourche,  S.  D  
Strawberry,  Utah  
Bumping  Lake  Wash 

12,000 
7,86o 
970 
40,080 
1,500 
25,000 
8,010 
8,370 

290,000 
70,000 
6,200 
2,368,000 
50,000 
462,000 
203,000 
100,000 

290,000 
40,000 

720,000 
40,000 
10,000 

203,000 
IOO,OOO 

1,580,000 
143,000 

4,866,000 
446,000 
138,000 

1,237,000 

612,000 

1915 
1892 
1912 
1916 
1908 
1910 
1911 
1913 
1910 

Lake  Kachess,  Wash  
Lake  Keechelus  Wash 

4,800 

2  55O 

210,000 

l8o,OOO 

840,000 

1912 
1917 

Shoshone,  Wyo  

6,600 

70,000 

47O,OOO 

1,350,000 

1910 

*  Built  by  Pecos  Irrigation  Co. 


EARTH  DAMS  AND  ROCKFILL  DAMS 


599 


TABLE  XLV.— EARTH  DAMS  AND   ROCKFILL   DAMS 


Name  and  Locality 

Purpose 

BUILT 

Crest 
L'gth 

Maxi. 
Hight 

Volume, 
Cu.  Yd. 

Cost 

By 

Year 

Arrowhead,  Cal  
Calaveras,  Cal  
Horseshoe  Bend,  Can  .... 
Las  Vegas,  N.  M  
Sugar  Loaf,  Col  
San  Pablo,  Cal  
Talla,  Scotland  
Dixville,  N.  H  
Laramie  River,  Wyo  

Power 
Domestic 
Irrig. 
Irrig. 
Indus. 
Domestic 
Domestic 
Power 
Irrig. 
Irrig. 

Private 
Private 
Private 
Public 
Private 
Private 
Public 
Private 
Private 

1908 
1901 

1894 

1911 
1897 
1893 
1899 
1884 
1875 

1890 
1893 
1895 

1914 
1913 
1872 

850 
1,300 
7,000 
1,400 
5,ooo 
1,300 
1,050 
500 
8,000 
12,709 
3,900 
635 
480 

I2OO 

975 

380 
565 
1,686 
IOO 

2,200 
850 
640 
1,380 
1,686 
470 
550 
365 
1,300 

I,  IOO 

1,  060 

2,080 
505 
425 

57 
4i 
75 
33 
40 
30 
47 

222 
24O 

45 
75 
40 
165 
80 
76 
34 
58 
47 
41* 
54 
116 
190 

76 
161 

52 

83 
50 
93 
95 
48 
52 
55 
69 
101 

IOO 

77 
106 
265 

IOO 

1,273 
886 
1312 
510 
682 
351 
78i 

3,085,000 
1,000,000 
450,000 
90,200 
1,500,000 
500,000 
83,500 
344,000 

127,655 

54-400 
44,965 

86,946 

200,000 

40,000 

170,000 
17,000 
124,000 
143,000 

200,000! 

I.IOO.OOO1 

151,521 

Balmorhea  Tex 

Irrig. 
Irrig. 
Domestic 
Domestic 
Power 
R.  cont'l 
Irrig. 
Domestic 
Irrig. 
Irrig. 
Irrig. 
Domestic 
Domestic 

Private 
Private 
Public 
Public 
Private 
Public 
Private 
Private 
Private 
Private 
Private 
Public 
Public 

Public 
Public 

Public 
Private 
Private 
Private 
Private 

Private 
Private 
Private 
Private 
Private 
Private 
Private 

84,000 

732,000 

2,130,000 
21,000,000 
37,159 
180,000 
102,400 

McAlester  Okla. 

Xinder  River  Eng. 

Necaxa,  Mexico  
Gatun,  Panama  
Escondido,  Cal  
Lower  Otay,  Cal  
McMillan,  N.  M  
E.  Canyon  Creek,  Utah  .  . 
Merced,  Cal  
San  Andres,  Cal  
Pilarcitos,  Cal  
Pecos  Valley,  No.  i,  N.  M. 

Pecos  Valley  No  2  N  M 

38,000 

680,000 
651,000 

306,000 
5S,ooo 

270,400 
58,890 
497,250 
41,808 
7.6,634 
42,510 
59,800 

La  Mesa,  Cal  

Lagastrello  Italy 

Irrig. 
Irrig. 

Domestic 
Flood 
Power 
Domestic 

Power 
Power 
Power 
Power 
Power 
Power 
Power  , 

Domodossola  Italy. 

Sevier  R.,  Utah  
Morris,  Conn  . 

Throttle,  N.  M  
Somerset  
Morena,  Cal  
Bowman,  Cal  

Seros  Project  Dams: 
No.  i  
No.  2  

No   3 

No.  4 

No.  5 

No.  6  
No.  7  

1  With  accessories. 


600 


TABLES 


TABLE  XLVI.— MASONRY  DAMS 


Name  and  Locality            Purpose 

BUILT 

Crest 
L'gth 

Max. 
Hight 

Volume, 
Cu.  Yd. 

Cost 

By 

Year 

Arrowrock,  Ida  
Ash  Fork,  Ariz  
Assiout,  Egypt  
Assuan,  Egypt  
Auckland,  N.  Zealand  
Azischos,  Maine  

Irrig. 
Railroad 
Irrig. 
Irrig. 
Domestic 
Power 
Domestic 
Irrig. 
Power 

Public 
Private 
Public 
Public 
Public 
Private 
Public 
Public 
Private 

Public 
Private 
Public 
Public 
Public 
Public 
Public 
Public 
Public 
Public 
Private 
Public 
Public 
Private 
Public 
Public 
Public 
Public 
Private 
Private 
Public 
Public 
Public 
Public 
Public 
Private 
Public 
Public 
Private 

Public 
Private 
Private 
Public 
Public 
Public 
Private 
Private 
Private 
Private 
Public 
Private 

IQI5 
1898 
1902 
1912 

1870 

1909 
1903 
1911 
1912 
1890 
1897 
1891 
1912 
1906 
1870 

1886 

1908 
1892 

1902 
1909 
1911 
1914 

1910 
1894 
1916 
1891 
1866 

1875 
1882 
1913 
1904 
1873 
1913 

1904 
1913 

1912 

1890 
I9IS 
1913 

IIOO 

300 
2769 
6400 
533 
881 

715 
625 
472 
784 
363 
580 
3296 
4067 
918 
2150 
670 
530 
640 
580 
811 

1300 
787 
755 
986 
IIOO 

170 

IIIO 

250 
590 
1674 
476 
330 
700 
771 
492 
233 
410 
755 

1200 
4OO 
1300 
1210 
834 
IO8O 
140 

677 
207 
1850 
4278 

349 
46 
48 
131 
7i 
78 
157 
188 
185 
95 
240 
92 

ITO 
64 
130 
203 
114 
78 

US 
42* 
125 

102 

180 

585.130 
1,500 
221,694 
1,179,000 

132,000 
140,000 

320,000 
4,684 
60,000 

332,000 
255,327 
27,000 
50,000 

58,400 
146,242 

4,404,000 
45,776 
2,450,000! 
18,660,000 

190,000 
465,000 

Badana    Italy 

Barker    Colo 

3,68o,ooo2 
133,528 
570,000 
170,000 
404,800 
i,4i6,ooo4 
i,500,ooo3 
370,000 
130,000* 

Barren  Jack,  Australia  .... 
Big  Bear  Valley,  Cal  
Beetaloo,  Australia  
Betwa,  India  
Bhatgur,  India  
Bober,  Germany  
Boonton,  N.  J  
Boyds  Corner,  N.  Y  
Brasimone,  I+alv  

Irrig. 
Irrig. 
Domestic 
Irrig. 
Irrig. 
Power 
Domestic 
Domestic 
Domesdc 
Domestic 
Domestic 
Domestic 
Domestic 
R.  cont'l 
Domestic 
Domestic 
Domestic 
Domestic 
Irrig. 
Domestic 
Irrig. 
Domestic 
Irrig. 
Power 
Fid.  prot. 
Power 
Domestic 
Domestic 
Irrig. 

Irrig. 
Power 
Power 
Domestic 
Domestic 
Irrig. 
Domestic 
Indus. 

Power 
Domestic 
Power 

Bridgeport,  Conn  
Cabbage  Tree,  Australia.  .  . 
Cataract,  Australia  
Chartrain,  France  
Chaustiere,  Canada  
Chuviscar,  Mexico  
Coolgardie,  Australia  
Cross  River,  N.  Y  
Croton  Falls,  N.  Y  
Crowley  Creek,  Ore  
Derwent,  England  
East  Park,  Cal  
Einsidedel,  Germany  
Elephant  Butte,  N.  M  .  .  .  . 
Folsom    Cal  

1,602,000 
420,000 

174 
197 
170 
173 
60 
114 
139 
93 
318 
98 
170 

112 

154 

121 
70 
96 
197 
76 

50 
96 

124 
25 
117 

100 

61 

47 
310 
37 

156,467 
290,540 
800 

1,389,120 

12,500 

12,200 
3I,6OO 
6O5,2OO 
48,590 
52,300 
8,5OO 
325,000 

14,422 

24,000 
I4O,OOO 

155,727 
312,500 
4,913,000 

318,000 

Furens  France  

Gem  Lake    Cal 

874,000 
109,194 

114,290 
46,000 

Gorzente,  Italy  

Granite  Springs,  Wyo  
Habra,  Algiers  
Male's  Bar,  Tenn  
Hatfield,  Wis  
Hemlock,  Conn  
Henne,  Germany  
Hindia  Barrage,  Mesopot.. 
Howden,  England  
Huacal,  Mexico  
Hume-Bennett  
Indian  River,  N.  Y  
Kensico,  N.  Y  
Keokuk,  la  

4,988 
2,207 

913.050 

Contract  price. 


-  Estimated. 


Approximate 


4  With  accessories. 


MASONRY  DAMS 


601 


TABLE  XLVI.— MASONRY  DAMS—  Continued 


Name  and  Locality 

Purpose 

BUILT 

Crest 
L'gth 

Max. 
Hight 

Volume, 
Cu.  Yd. 

Cost 

550,000 
500,000 

630,000 
300,000! 
243,750 

By 

Year 

La  Boquilla,  Mexico  
La  Grange,  Cal  

Irrig. 
Irrig. 

Domestic 
Irrig. 
Irrig. 

Domestic 
Irrig. 
Flood 

Irrig  
Irrig. 
Domestic 
Domestic 
Domestic 
Irrig. 
Power 
Flood 

Domestic 

Domestic 
Irrig. 
Irrig. 
Domestic 
Irrig. 
Power 
Irrig. 

Domestic 

Irrig. 
Domestic 

Power 
Domestic 
Irrig. 
Domestic 
Domestic 
Domestic 

Domestic 
Domestic 
Domestic 
Domestic 
Domestic 
Storage 
Flood 
Power 
Domestic 

Private 

1894 
1902 
1904 

1909 
1895 
1913 

1905 
1912 
1913 
1905 

1917 
1906 

1911 
1905 

1878 
1909 
1897 
1892 
1911 
1907 
1914 

1889 
1898 
1910 
1893 
1916 
1905 

1888 
1891 

1895 
1913 
1904 
1889 

1878 

1906 
1902 
1894 
1907 

1843 

840 

320 

1800 
710 
5136 
360 
840 

880 
427 
918 
1580 
535 

2IOO 

I20O 
l800 

490 
750 
1  IOOO 

14650 

432 
1231 

1125 

480 
592 
580 
643 
200 
50O 
155 
552 
1250 
380 
8800 

534 
148 
741 
T350 
547 
900 
1476 
600 
385    • 
367 
1400 
205 

261 
129 
87 
227 
98 
135 
98 

200 
I48 

203 
180 
133 
131 
IOO 
238 
85 
132 
88 

251 

H3 
218 
173 
82 
280 
135 
225 
151 
146 
68 
328 
98 
50 
150 
144 
98 
118 
124 
109 
50 
190 
136 
170 
160 
228 
75 
46 
95 
217 

123 

390,000 
39,500 
92,000 
103,000 
360.000 
32,500 
37,400 
140,000 

83,700 
332,000 
205,000 
28,000 

353,000 
8,300 
855,000 
92,000 
85,000 
36,200 

488,200 

60,210 
185,000 
22,886 
342,325 
63,000 

139,000 

28,511 
78,576 
35,887 

180,000 

20,507 
408,520 

149,000 
260,000 

Lake  Cheesman,  Cal  
Lake  Fife  India 

Public 
Private 

Public 
Private 
Private 
Public 
Private 
Private 
Public 
Public 
Public 
Public 
Private 
Public 

Public 

Public 
Public 
Public 
Public 
Public 
Private 
Private 
Private 
Private 
Private 
Public 
Public 

Private 
Public 
Private 
Public 
Public 
Public 

Private 
Public 
Publ'.c 
Private 
Public 
Public 
Private 
Public 
Private 
Public 

La  Prele  Wyo 

Lauchensee,  Germany  
Lister,  Germany  
Little  Bear  Valley,  Cal.  .  .  . 

595,000 
1,416,000 

200,000 

5,000,000* 
•    90,000 

6,886,872 

540,000 

204,000 
853,200' 
256,000 

91,154 
3,893,000 

400,000 

150,000 
1,356,000 
366,499 

234,074 

988,000 

204,372 
933,065! 

Medina,  Tex  
Mercedes,  Mexico  

Mountain  Dell,  Utah  
New  Croton,  N.  Y  
New  Dam,  Mexico  
New  Hauser,  Mo  

Olive  Bridge,  N.  Y  

Pas  Du  Riot,  France  
Pathfinder,  Nebr  
Periar,  India  
Remscheid,  Germany  

Rio  Das  Lages,  Brazil  
Salmon  River,  Idaho  
San  Jose,  Mexico  
San  Mateo,  Cal  
Seligman,  Ariz  

Sodom  N  Y 

Scovell  Creek,  Australia  .  . 
Spiers  Falls,  N.  Y  
Swanzy,  Wales  
Sweetwater,  Cal  
Tansa,  India  
Ternay,  France  
Titicus,  N.  Y  
Triunfo  Creek,  Cal  
Urft,  Germany  
Vyrnwy,  Wales  
Villar,  Spain  
Waldeck,  Germany  
Wauchusetts,  Mass  
Wigwam,  Conn  
Williams,  Ariz  
Wofelsgrund,  Germany.  .  .  . 
Yadkin  Narrows,  N.  C.  .  .  . 
Zola,  Spain  

2,957,000 
390,000 
1,880,9502 
2,378,206 
150,000 

52,833 

102,000 

274.439 
14,887 
5,226 
26,200 
525,000 

1  Contract  price. 


2  Estimated. 


3  Approximate. 


4  With  accessories. 


602  TABLES 


VELOCITY  TABLES 

Tables   XL VII   to  LIII   give   the  values  of   the  mean  velocity  of  water  in 
open  channels  computed  from  Kutter's  formula: 

1.811  ,  ,  0.00281 

-+4I.6+— 
n  s 


0.00281  )     n 


The  values  of  n,  the  coefficient  of  roughness,  to  be  used  in  finding  v,  depend  on 
the  roughness  of  the  materials  forming  the  bed  and  banks  of  the  channel,  irregu- 
larities and  imperfections  in  the  bed  or  banks,  curves,  eddies,  aquatic  plants, 
and  other  conditions  that  tend  to  produce  a  retardation  of  flow.  Experimental 
data  on  the  subject  are  limited  and  the  commonly  accepted  values  of  n  for  specific 
conditions  must  be  considered  as  mere  approximations.  These  approximate 
values,  based  on  a  consideration  of  the  data  available,  are  as  follows: 
n  =  0.010  for  clean,  straight  channels  of  planed  lumber  carefully  laid;  neat  cement 

plaster;  glazed,  coated  and  enameled  surfaces  in  perfect  order. 
n  =  0.012  for  clean,  straight  and  regular  channels  of  planed  boards  not  in  perfect 
order  due  to  inferior  workmanship  or  age;  unplaned  boards  carefully  laid; 
metal  flumes  of  the  smooth  interior  type  and  gentle  curvature  in  alinement; 
concrete  linings  having  steel  troweled  surfaces  of  i  :  i  mortar,  sand  and 
cement  plaster;  clean  brickwork. 

n  =  0.014  for  clean,  regular  channels  of  concrete  having  wooden  troweled  or  formed 
surfaces  of  good  construction,  the  alinement  consisting  of  tangents  connected 
by  gentle  curves;  unplaned  boards  not  in  perfect  order  due  to  inferior  work- 
manship or  age. 

n  =  0.015  for  construction  as  in  the  preceding  case  but  with  sharp  curvature  or 
with  deposits  of  silt  on  the  bottom  of  channel;  straight  and  regular  channels 
of  ordinary  brickwork;  smooth  stonework;  foul  and  slightly  tuberculated 
iron. 

w  =  o.o2o  for  channels  of  fine  gravel;  rough  rubble;  or  tuberculated  iron;  or  for 
canals  in  earth,  in  good  condition,  lined  with  well-packed  gravel,  partly 
covered  with  sediment,  and  free  from  vegetation. 

n  =  0.0225  for  canals  in  earth  in  good  condition,  or  composed  of  loose  gravel  with- 
out vegetation. 

n  =  0.025  for  canals  and  rivers  of  tolerably  uniform  cross-section,  slope  and  direc- 
tion in  average  condition. 

n  =  0.030  for  canals  and  rivers  in  rather  poor  condition,  having  bed  partially  cov- 
ered with  debris,  or  having  comparatively  smooth  sides  and  bed  but  a  chan- 
nel partially  obstructed  with  grass,  weeds  or  aquatic  plants. 

n  =  0.035  f°r  canals  and  rivers  in  bad  order  and  regimen,  having  the  channel 
strewn  with  stones  and  detritus  or  about  one-third  full  of  vegetation. 


VELOCITY  TABLES  603 

Canals  in  earth  with  their  channels  half  full  of  vegetation  may  have  n  ='0.040, 
and  when  two-thirds  full  of  vegetation  may  have  n  =  0.050.  In  exceptional  cases 
the  value  of  n  may  reach  0.060. 

As  an  indication  of  the  extent  to  which  the  value  of  n  affects  the  velocity  of  the 
discharge  of  channels,  let  us  take  an  example  in  which  n  =  0.02 25.  A  bed  width 
of  10  feet,  depth  of  2  feet,  and  side  slopes  of  i  to  i,  with  a  grade  of  8  feet  per  mile, 
gives  a  velocity  of  3.32  feet  per  second  and  a  discharge  of  79.07  second-feet.  For 
the  same  channel  with  a  value  of  n=  0.035  the  velocity  is  2.05  feet  per  second  and 
the  discharge  49.2  second-feet;  thus  showing  that  with  the  better  channel  the  dis- 
charge is  60  per  cent  greater  than  with  the  inferior  channel. 

NOTE. — To  find  velocities  for  slopes  other  than  those  given  in  this  table,  multiply 
the  tabular  velocity  found  in  the  column  of  "  ^  =  52.80  "  by  ten  times  the  square  root 
of  the  slope.  The  velocity  thus  obtained  is  accurate  for  slopes  greater  than  6  feet 
per  mile,  and  approximate  for  all  slopes  greater  than  4  feet  per  mile. 


604 


TABLES 


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607 


oio-=  S' 
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MOOttoO      t-  00   ON  ON  O 


M    ONO    MOO       t  O  O    M    t-~      MOO    OOOO    OO     00 


I  O     OO   ONOO  O 


900-  =$• 

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Ol7-9Z=. 


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l700  •=$• 

ZI-IZ  =  £ 


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MMOooot     lOiOOOt^     t^oooOONO\     OO»-'l-<M      nc\ic^oooo     rt't'T'totoOoOONM 


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M   t-  ON  • 

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-OOOO       OOONONOlO        OOMMM        MMMOOl 


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9$-oi  =  d 


OONMM      t^ONOoOO      t-nioooOM      MwOoOO      MONTOto     ON 
M    M    M    OO      OO  <*•  t  -<t  tO      IOIOOOO       t^I>t^OOOO 


000      00   O  ON 
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o  o  o  oo 


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t-  M     O   ON  M  iO( 
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608 


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oio-=  9 

08-2£=.!/ 


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609 


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Vgz  =  jj 

U3d   ^3M 

CM    tO  00    O       CM    tO  00    O       CM    tO  00    O       <N    tO  00    O       CM    tO  OO    O       CM    tO  00    O       OOO 

B3JB 

00001      MMMMCM      CMNCMCMro     POPOroro4     444tlO     10  10  10  100      t-CCOO     j 

VELOCITY  TABLES  611 

TABLE  LIV.— AREA  IN   SQUARE    FEET,  A,  AND    HYDRAULIC    RADIUS;  r,  OF 
TRAPEZOIDAL  CHANNELS,  SIDE  SLOPES  2  :  i 


£ 
"a 

u 
Q 

BOTTOM  WIDTH  IN  FEET. 

A 
r 

4 

6 

8 

10 

12 

14 

16 

18 

20 

25 

30 

40 

50 

i  .0 

6.0 

.71 

8.0 
.76 

IO.O 

.80 

12.  O 

.83 

14.0 
.85 

16.0 

.87 

18.0 
.88 

20.0 
.89 

22.0 
.90 

27.0 
.92 

32.0 
•  93 

42.0 
•  94 

52.0 
•  95 

i.  5 

A 
r 

10.5 
.98 

13-5 
i.  06 

16.5 

I  .  12 

19-5 

1.16 

22.5 
I  .22 

25-5 
1.23 

28.5 
1.25 

31-5 
1.28 

34-5 
1.30 

42.0 
1.32 

49-5 
1.35 

64-5 
1.38 

79-5 
1.40 

2.0 

A 
r 

16.0 
1.24 

20.0 
1.33 

24.0 
I.4I 

28.0 
1.48 

32.O 
1.52 

36.0 
1-57 

40.0 
i.  60 

44.0 
1.63 

48.0 
1.66 

58.0 
1.71 

68.0 
1-75 

88.0 
i.  80 

108 
1.83 

2.5 

A 
r 

22.5 
1.48 

27-5 
1.  60 

32.5 
1.70 

37-5 

1-77 

42.5 

1.83 

47-5 
1.88 

52.5 
1-93 

57  •  5 
1-97 

62.5 

2.00 

75.0 
2.07 

87.5 

2.12 

H3 

2.20 

138 
2.25 

3.0 

A 
r 

30.0 

1.72 

36.0 
1.85 

42.0 
1.96 

48.0 
2.05 

54-0 
2.12 

60.0 
2.19 

66.0 

2.24 

72.0 
2.29 

78.0 
2  .34 

93-0 

2.42 

108 

2.48 

138 
2.58 

168 
2.65 

3.5 

A 
r 

38.5 
1.96 

45-5 
2.  10 

52.5 
2.22 

59-5 
2.32 

66.5 
2.40 

"3-5 
2.48 

80.5 

2.54 

87.5 
2.60 

94-5 
2.65 

112 
2.82 

130 

2.84 

165 
2.96 

200 
3.04 

4.0 

A 
r 

48.0 
2.19 

56.0 

2.34 

64.0 

2.47 

72.0 

2.58 

So.o 
2.68 

88.0 
2.76 

96.0 
2.83 

104 
2.90 

112 
2.96 

132 
3.08 

152 

3-  17 

192 
3-32 

232 
3.42 

4.5 

A 
r 

58.5 
2.42 

67.5 
2.58 

76.5 
2.72 

85.5 
2.84 

94-5 
2.94 

104 
3-04 

113 
3-  II 

122 
3-18 

131 
3-25 

153 
3-39 

176 
3-50 

221 
3-67 

266 
3.78 

5.0 

A 
r 

70.0 
2.65 

80.0 
2.82 

90.0 
2.96 

IOO 

3.09 

no 
3.20 

120 
3-30 

130 
3-39 

140 
3-47 

150 
3-54 

175 
3-70 

200 
3-82 

250 
4.01 

300 
4-15 

5-5 

A 
r 

82.5 
2.89 

93-5 
3.06 

105 

3-21 

116 
3-34 

127 
3-46 

138 
3.56 

149 
3-66 

160 
3-75 

171 

3.82 

198 
3-99 

226 
4-13 

28l 

4-34 

335 
4-50 

6.0 

A 
r 

96.0 
3.  II 

108 
3.29 

I2O 
3-45 

132 
3-59 

144 
3-71 

156 

3-8.? 

168 
3-93 

180 
4.02 

192 
4.  10 

222 
4.28 

252 
4-43 

312 

4.67 

372 

4-85 

6.5 

A 
r 

III 
3-34 

124 
3-52 

137 
3.68 

148 
3-84 

163 
3.96 

176 
4.08 

189 

4-18 

202 
4.28 

215 

4.38 

247 

4-57 

280 
4-73 

345 
4-98 

410 
5-18 

7-0 

A 
r 

126 
3.57 

140 
3-75 

154 
3-92 

168 
4-07 

182 
4.20 

196 
4-33 

2IO 

4-44 

224 

4-54 

238 

4.64 

273 

4-85 

308 
5.02 

378 
5-30 

448 
5-51 

7-5 

A 
r 

142 
3-80 

158 
3-98 

172 

4-15 

188 
4-31 

2O2 

4-45 

218 
4-58 

232 
4-69 

248 
4.80 

262 
4.90 

300 

5-12 

338 
5-31 

412 
5.6i 

488 
5-84 

8.0 

A 
r 

160 
4.02 

176 
4.21 

192 
4-39 

208 

4-54 

224 
4-69 

240 
4.82 

256 
4-94 

272 
5-05 

288 

5.16 

328 

5.40 

368 
5-59 

448 
5-91 

528 
6.16 

8.5 

A 
r 

178 
4-25 

195 
4-44 

212 

4.62 

230 

4-78 

246 
4-93 

264 
5-07 

280 
5-19 

298 
5-31 

314 

5.42 

357 
5-66 

400 
5.8? 

484 

6.21 

570 
6.47 

9-0 

A 
r 

198 
4-47 

216 

4.67 

234 
4-85 

252 
5-01 

270 
5-17 

288 
5-31 

306 
5-44 

324 
5-56 

342 

5-68 

387 
5-93 

432 
6.15 

522 
6.51 

612 
6.78 

10.  0 

A 
r 

240 

4-93 

260 

5.  13 

280 
5-31 

300 

5.48 

320 

5-64 

340 
5-80 

360 
5-94 

380 
6.06 

400 
6.18 

450 
6.45 

500 
6.69 

600 
7.09 

700 
7-40 

612 


TABLES 


FIG.  250. — Standard  Horseshoe  and  Circular  Sections  for  Conduits. 


TABLE  LV.      AREA,    WETTED    PERIMETER    AND    HYDRAULIC    RADIUS   OF 
PARTIALLY  FILLED  HORSESHOE  AND  CIRCULAR  CONDUIT  SECTIONS 


HORSESHO 

E  SECTIONS 

CIRCULAR 

SECTIONS 

Depth. 

Area 

Wet.  per. 

Hyd.  rad. 

Depth. 

Area. 

Wet.  per. 

Hyd.  rad. 

R 

R> 

R 

R 

R 

R* 

R 

R 

0.  I 

0.0887 

1  .2702 

o  .  0066 

0.177 

o.  1961 

1.6962 

o.  1156 

O.  I 

0.0587 

0.9020 

0.0561 

0.2 

0.2340 

1.7462 

o.  1340 

O.2 

0.1635 

I  .2870 

o.  1270 

0.3 

0.4050 

1.9620 

0.2064 

0.3 

0.2955 

1.5908 

0.1858 

0.4 

0.5828 

2.1736 

0.2681 

0.4 

0.4473 

1.8546 

0.2413 

o.S 

0.7656 

2.3816 

0.3230 

0.5 

0.6142 

2  .  0944 

0.2936 

0.6 

0.9573 

2.5869 

0.3700 

0.6 

0.7927 

2.3186 

0.3410 

0.7 

I.  1510 

2.7900 

0.4126 

0.7 

0.9799 

2.5322 

0.3870 

0.8 

1.3478 

2.9916 

0.4505 

0.8 

I.  1735 

2.7389 

0.4285 

0.9 

I  •  5407 

3.1922 

0.4845 

0.9 

I.37H 

2.9412 

0.4662 

I.O 

1-7465 

3.3923 

0.5148 

I.O 

1.5708 

3.1416 

0.5000 

.  i 

1.9462 

3.5926 

0.5417 

i.i 

1-7705 

3.3419 

0.5298 

.  2 

2.1438 

3  .  7949 

0.5649 

1.2 

I  .9681 

3  -  5443 

0.5553 

•  3 

2.3374 

4.0017 

0.5841 

1.3 

2.  l6l7 

3-7510 

0.5763 

•  4 

2.5246 

4-2153 

0.5989 

1.4 

2.3489 

3  •  9646 

0.5925 

.5 

2.7031 

4-4395 

0.6089 

1.5 

2.5274 

4.  1888 

0  .  6034 

.6 

2.8700 

4-6793 

0.6134 

1.6 

2  .  6943 

4.4286 

0.6084 

.7 

3.0218 

4-9431 

0.6113 

1.7 

2.8461 

4.6924 

0.6065 

.8 

3.1538 

5  -  2469 

0.6011 

1.8 

2.9781 

4.9962 

0.5961 

•  9 

3.2586 

5.6318 

0.5786 

1.9 

3.0829 

5.38II 

0.5729 

2.0 

3.3173 

6.5339 

0.5077 

2.O 

3.I4I6 

6.  2832 

0.5000 

NOTE. — Figures  in  first,  third  and  fourth  columns  are  to  be  multiplied,  by  adopted  value 
of  R.     Figures  in  second  column,  by  R-. 


VELOCITY  TABLES 


613 


TABLE  LVI.  AREA  IN  SQUARE  FEET,  A,  AND  HYDRAULIC  RADIUS  IN 
FEET,  r,  OF  SEMI-CIRCULAR  FLUMES  FOR  VARIOUS  VALUES  OF  FREE- 
BOARD IN  FEET.  F 


Diam- 

F = 

0.2 

F  = 

0.3 

F  = 

0.4 

F  = 

o.S 

F  = 

0.6 

Flume 

eter 

No. 

in 

Feet 

A 

r 

A 

r 

A 

r 

A 

r 

A 

r 

24 

1.273 

0-39 

0.24 

0.27 

o.  20 

30 

I.S92 

0.68 

0.32 

0-53 

o.  28 

0.38 

0.23 

0.25 

0.18 

36 

1  .910 

1.05 

0.41 

0.87 

0.36 

0.69 

0.32 

0.52 

0.27 

42 

2.228 

i.SO 

0.48 

1.29 

0.45 

i.  08 

0.40 

0.87 

0.36 

0.68 

0.31 

48 

2.546 

2.04 

0.57 

1-79 

0.53 

1.54 

0.49 

1.31 

0-44 

i.  08 

0.39 

60 

3-183 

3-34 

0.73 

3-03 

0.69 

2.72 

0.65 

2.41 

0.61 

2  .  II 

0.56 

72 

3.820 

4-97 

0.89 

4-59 

0.85 

4.21 

0.81 

3.84 

0.77 

3-48 

0.73 

84 

4.456 

6.91 

1.05 

6.47 

.01 

6.03 

0.98 

5-59 

0.93 

5.16 

0.89 

96 

5-093 

9-17 

I  .21 

8.66 

•  17 

8.16 

•  13 

7.66 

i  .09 

7.16 

.06 

108 

5-730 

ii.  8 

1.29 

II  .  2 

•  33 

10.6 

.29 

10.  0 

1.26 

9.48 

.22 

I2O 

6.366 

14.6 

1.53 

14.0 

•49 

13-4 

•  45 

12.7 

1.42 

12.  I 

•  38 

132 

7.003 

17.9 

1.69 

17  .2 

.65 

16.5 

.61 

15-8 

1.58 

I5.I 

•  54 

144 

7.639 

21.4 

1.84 

20.  6 

.81 

19.9 

•  77 

19.1 

1-74 

18.4 

.70 

156 

8.276 

25-2 

2.OO 

24.4 

•  97 

23.6 

•93 

22.8 

1.90 

21.9 

.86 

168 

8.913 

29.4 

2.  16 

28.5 

.13 

27.6 

.09 

26.7 

2.06 

25-9 

2.02 

180 

9-549 

33-9 

2.32 

32.9 

.29 

32.0 

•25 

31.0 

2.22 

30.1 

2.18 

192 

10.  186 

38.7 

2.48 

37-7 

•  45 

36.7 

.42 

35.7 

2.38 

34-6 

2.34 

204 

10.823 

43.8 

2.64 

42.8 

.61 

41.7 

•  57 

40.6 

2.54 

39-5 

2.50 

216 

11-459 

49-3 

2  .  8O 

48.  i 

.76 

47.0 

•  73 

45-8 

2.70 

44-7 

2.66 

228 

12.096 

55-0 

2.96 

53-8 

•  93 

52.6 

.89 

51-4 

2.86 

50.2 

2.82 

240 

12.732 

61.1 

3-12 

59-8 

3.08 

58.6 

3-05 

57-3 

3.01 

56.0 

2.98 

252 

13-369 

67.5 

3.26 

66.2 

3.24 

64.8 

3-21 

63.5 

3.18 

62.2 

3-14 

Diam- 

F = 

0.8 

F  = 

I.O 

F  = 

1.2 

F  = 

1.4 

F  = 

i.S 

Flume 

eter 

No. 

in 

Feet 

A 

r 

A 

r 

A 

r 

A 

r 

A 

r 

72 

3.820 

2.76 

0.64 

2.08 

0-54 

84 

4-456 

4-31 

0.80 

3-49 

0.71 

2.71 

0.61 

96 

5-093 

6.18 

0.97 

5-22 

0.88 

4-30 

0.78 

3.41 

0.68 

108 

5-730 

8.37 

1.14 

7.28 

1.05 

6.22 

0.96 

5-19 

0.86 

4.69 

0.81 

120 

6.366 

10.9 

1.30 

9.65 

I  .21 

8.46 

I  .  12 

7-29 

1.03 

6.72 

0.98 

132 

7.003 

13-7 

1  .46 

12.4 

1-38 

II  .O 

1.29 

9-72 

i  .  20 

9.07 

i.  IS 

144 

7.639 

16.9 

1.62 

15-4 

1-54 

13-9 

1.46 

12.5 

1.37 

11.  8 

1.32 

156 

8.276 

20.3 

1.79 

18.7 

1.70 

17-  I 

1.62 

15-5 

1.53 

14.8 

1-49 

168 

8.913 

24.1 

1.95 

22.4 

1.87 

20.6 

1.78 

18.9 

1.70 

18.1 

1.65 

1  80 

9-549 

28.2 

2  .  II 

26.3 

2.03 

24.5 

1.95 

22.6 

1.86 

21.7 

1.82 

192 

10.186 

32.6 

2.27 

30.6 

2.  19 

28.6 

2.  II 

26.7 

2.03 

25-7 

1.98 

204 

10.823 

37-4 

2-43 

35-2 

2.35 

33.1 

2.27 

31-0 

2.19 

3O.O 

2.14 

216 

11-459 

42-4 

2.59 

40.2 

2-51 

37-9 

2.43 

35-7 

2.35 

34-6 

2.31 

228 

12  .096 

47-8 

2.75 

45-4 

2.67 

43-0 

2.60 

40.7 

2.52 

39-5 

2.47 

240 

12.732 

53-5 

2.91 

5i   o 

2.83 

48.5 

2.76 

46.0 

2.68 

44-7 

2.63 

252 

13.369 

59-4 

3-07 

56.9 

2.99 

54-2 

2.92 

51.6 

2.84 

50.3 

2.80 





614 


TABLES 


TABLE  LVII. 


THEORETICAL  VELOCITY  OF  WATER  IN   FEET  PER  SECOND 
FOR    VARIOUS    HEADS 


V=\/2gh.     g  =32.16 


Head 

in  Ft. 

O.OO 

O.OI 

O.O2 

0.03 

0.04 

0.05 

0.06 

0.07 

0.08 

0.09 

0.  I 

2.536 

2.660 

2.778 

2.892 

3.OOI 

3.106   3.208 

3.307   3-402 

3.496 

0.2 

3-586 

3.675 

3.762 

3  •  846 

3.929 

4  oio 

4.089 

4.167 

4.244 

A  -319 

0.3 

4  •  393 

4.465 

4.536 

4.628 

4-676 

4  •  745 

4.812 

4.878 

4  •  944 

5  .  008 

0.4 

5.072 

5.135 

5-197 

5  •  259 

5-320 

5.38o 

5-439 

5  -  498 

5.556 

5-614 

0.5 

5.671 

5.727 

S.7S3 

5  .  838 

5.893 

5-947 

6.001 

6.054 

6.  107 

6.160 

0.6 

6.  212 

6.263 

6.315 

6.365 

6.416 

6.465 

6.525 

6.564 

6.613 

6.662 

0.7 

6.  710 

6.757 

6.805 

6.852 

6.899 

6.946 

6.992 

7.038 

7.083 

7.128 

0.8 

7.173 

7.218 

7  .  262 

7.306 

7-350 

7-394 

7.438 

7.481 

7.523 

7.566 

0.9 

7.608 

7-650 

7.692 

7-734 

7.776 

7.817 

7.858 

7-898 

7-939 

7-979 

1.0 

8.020 

8.060 

8.099 

8  139 

8.  179 

8.218 

8.257 

8.296 

8.335 

8.373 

i  .  i 

8.412 

8.450 

8.487 

8.525 

8.563 

8.600 

8.638 

8.675 

8.712 

8.749 

I  .  2 

8.785 

8.822 

8.858 

8.894 

8.930 

8.967 

9.002 

9-038 

9-073 

9.  108 

1-3 

9  .  144 

9.179 

9-214 

9-249 

9  .  284 

9-3T8 

9-353 

9.387 

9-421 

9-455 

1-4 

9.489 

9.523  9-557 

9-590 

9.624 

9.657 

9.690 

0.724 

9-757 

9-790 

1.5 

9.822 

9.855 

9.888 

9.920 

9-953 

9.985 

10.017 

10.049 

10.081 

10.  113 

1.6 

10.145 

10.  176 

10.208 

10.239 

10.  271 

10.302 

10.333 

10.364 

10.395 

10.425 

1.7 

10.457 

10.487 

10.518 

10.549 

10.579 

10.611 

10.640 

10.670 

10.712 

10.730 

1.8 

10.760 

10.790 

10.820 

10.849 

10.879 

10.908 

10.938 

10.967 

10.996 

ii  .026 

1.9 

11.055 

ii  .084 

ii  .  113 

11.142 

11.171 

i  i  .  199 

11.228 

11.257 

11.285 

11.314 

Head 

in  Ft. 

o.o 

O.  I 

O.  2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

2 

II.  3 

ii.  6 

II.  9 

12  .  2 

12.4 

12.7 

12.9 

13.2 

13-4 

13-7 

3 

13.9 

14.1 

14-3 

14-6 

14-8 

15.0 

15.2 

15-4 

15-6 

15-8 

4 

16.0 

16.2 

I6.4 

16.6 

16.8 

17.0 

17.2 

17-4 

17.6 

17.8 

5 

17-9 

18.1 

18.3 

18.5 

18.6 

18.8 

19.0 

19.2 

19.3 

19-5 

6 

19.6 

19.8 

20.  O 

20.  i 

20.3 

20.5 

20.6 

20.8 

20.9 

21  .  I 

7 

21  .  2 

21.4 

21.5 

21  .7 

21.8 

22.  O 

22  .  I 

22.3 

22.4 

22.5 

8 

22.  7    22.8    23  .O 

23.  1 

23  •  3 

23-4 

23-5 

23.7 

23-8 

23-9 

9    24.1   24.2 

24-3 

24.5 

24.6 

24.7 

24.8 

25.0 

25-1 

25-2 

10    25.4 

25.5 

25-6 

25.7 

25.9 

26.0 

26.  i 

26.  2 

26.4 

26.5 

II 

26.6 

26.7 

26.8 

27.0 

27.1 

27.2 

27.3 

27-4 

27.5 

27-7 

12 

27.8 

27-9 

28.0 

28.1 

28.2 

28.4 

28.5 

28.6 

28.7 

28.8 

13 

28.9 

29.0 

29-  I 

29.2 

29-4 

29-5 

29.6 

29  .  7    20.8 

29-9 

14 

30.0 

30.  I 

30.2 

30.3 

30-4 

30.5 

30.6 

30.7 

30.9 

31.0 

15 

31.  1 

31-2 

31.3 

31.4 

31-5 

31.6 

31-7 

31-8. 

31-9 

32.0 

16 

32.1 

32.2 

32.3 

32.4 

32.5 

32.6 

32.7 

32.8 

32.9 

33-0 

17 

33-1 

33-2 

33.3 

33.4 

33-5 

33  •  5 

33.6 

33-7 

33-8 

33-9 

18 

34-0 

34-1 

34.2 

34-3 

34-4 

34-5 

34-6 

34-7 

34-8 

34-9 

19 

35.0 

35-0 

35-  1 

35-2 

35-3 

35-4 

35-5 

35-6 

35-7 

35.8 

20 

35-9 

36.0 

36.0 

36.1 

36.2 

36.3 

36.4 

36.5 

36.6 

36.7 

21 

36.8 

36.8 

36.9 

37-0 

37-1 

37-2 

37-3 

37-4 

37-4 

37-5 

1 

VELOCITY  TABLES 


615 


TABLE    LVIII.       AVERAGE    WEIGHT,    IN    POUNDS    PER    CUBIC    FOOT,    OF 
VARIOUS    SUBSTANCES 


Substance 


Clay,  earth  and  mud: 

Clay 

Earth,  dry  and  loose 

Earth,  dry  and  shaken 

Earth,    dry    and    moderately 

rammed 

Earth,  slightly  moist,  loose 

Earth,  more  moist,  loose 

Earth  more  moist,  shaken  .... 
Earth,  more  moist  moderately 

rammed 

Eaith,  as  soft  flowing  mud  .... 
Earth,  as  soft  mud  well  pressed 

into  a  box 

Mud,  dry,  close 

Mud,  wet,  moderately  pressed. 
Mud,  wet,  fluid 

Masonry  and  its  materials: 

Brick,  best  pressed 

Brick,  common  hard 

Brick,  soft,  inferior.  . 

Brickwork,  pressed  brick,   fine 

joints 

Brickwork,  medium  quality.  .  . 
Brickwork,  coarse,  inferior  soft 

bricks 

Cement,  pulverized,  loose 

Cement,  pressed 

Cement,  set 

Concrete,  1:3:6 

Gravel,  loose 

Gravel,  rammed 

Masonry  of  granite  or  stone  of 

like  weight: 

Well  dressed 

Well-scabbled    rubble,    20    per 

cent  mortar 

Roughly    scabbled    rubble    25 

to  35  per  cent  mortar 

Well-scabbled  dry  rubble 

Roughly  scabbled  dry  rubble. 
Masonry  of  sandstone  or  stone  of 

like     weight     weighs     about 

seven-eignths  of  the  above: 


Weight 


122-162 
72-80 
82-92 

90-100 

70-76 
66-68 
75-90 

90-100 
104-112 

no- 1 20 

80-110 

i 10    130 

104-120 


150 
125 

TOO 
140 

125 

IOO 

72-105 

US 
168-187 

140 

82-125 
90-145 


165 
154 
150 

138 

125 


Substance 


Masonry  and  its  materials — Con- 
tinued. 

Mortar,  hardened 

Sand,  pure  quartz,  dry,  loose. 

Sand,  pure  quartz,  dry,  slightly 
shaken 

Sand,  pure  quartz,  dry,  rammed 

Sand,  natural,  dry,  loose 

Sand,  natural,  dry,  shaken. .  .  . 

Sand,  wet,  voids  full  of  water .  . 

Stone 

Stone  quarried,  loosely  piled.  . 

Stone,  broken,  loose 

Stone,  broken,  rammed 

Metals  and  alloys: 

Brass  (copper  and  zinc) 

Broaze  (copper  and  tin) 

Copper,  cast 

Copper,  rolled 

Iron  and  steel,  cast 

Iron  and  steel,  average 

Iron  and  steel,  wrought 

Iron  and  steel,  average 

Spelter  or  zinc 

Tin,  cast 

Woods,  seasoned  and  dry: 

Ash 

Hemlock 

Hickory 

Oak,  white 

Oak,  red,  black,  etc 

Pine,  white 

Pine,  yellow,  northern 

Pine,  yellow,  southern 

Poplar 

Spruce 

Woods  weigh  one-fifth  to  one- 
half  more  green  than  dry; 
and  ordinary  building  tim- 
ber, tolerably  seasoned, 
weighs  about,  one-sixth  more 
than  dry  timber. 


Weight 


90-115 
87-106 

92-110 

100-120 

8O-IIO 

85-125 

II8-I28 

135    195 

So-llO 

77    112 

79-121 


487-524 
524-537 
537-548 
548-562 
438-483 

450 
475-494 

481 

425-450 
450-470 


40-53 

25 

37-58 
37-56 
32-45 
22-31 
30-39 
40-50 
22-31 
25 


616  TABLES 


TABLE  LIX.     CONVENIENT  EQUIVALENTS 

LENGTH 

I  inch  =iV  foot  =.027778  yard  =.000015783  mile  =2.54  centimeters. 
I  foot  =  12  inches  =3  yard  =.00018939  mile  =.3048  meter. 
I  yard  =36  inches  =3  feet  =.00056818  mile  =.9144  meter. 
I  mile  =63360  inches  =5280  feet  =1760  yards  =  1.60935  kilometers. 

I  meter  =  100  centimeters  =.ooi  kilometer  =39-37     inches  =3.2808     feet  =  1.0936     yards  = 
.0006213?  mile. 

SURFACE 

I  square  inch  =.006944  square  foot  =.0007716  square  yard  =.0000001594  acre  =.000000- 

0002491  square  mile  =6. 45163  square  centimeters. 
I  square  foot  =144  square  inches  =£  square  yard  =.000022957  acre -.00000003587  square 

mile  =.092903  square  meters. 
I  square  yard  =1296  square  inches  =9  sqiiare  feet  =.0002066  acre  =.0000003228  square  mile 

=  .83613  square  meter. 
I  acre  =6272640  square  inches  =43560  square  feet  =4840  square  yards  =.0015625  square 

mile  =208.71  feet  square  =.404687  hectare. 
I  square  mile  =4014489600  square  inches  =27878400  square  feet  =3097600  square  yards  = 

640  acres  =259  hectares. 
I  square  meter  =  10000  square  centimeters  =.0001  hectare  =.000001  square  kilometer  =  1550 

square  inches  =  10.7639  square  feet  =1.19598  square  yards  =.0002471  acre  =.0000003861 

square  mile. 

VOLUME 

I  cubic  inch  =.004329  U.  S.  gallon  =.0005787  cubic  foot  =  16.3872  cubic  centimeters. 
I  U.  S.  gallon  =231  cubic  inches  =.13368  cubic  foot  =.00000307  acre-foot  =3.78543  liters. 
I  cubic  foot  =1728  cubic  inches  =7.4805  U.  S.  gallons  =.037037  cubic  yard  =.000022957 

acre-foot  =28.317  liters. 

I  cubic  yard  =46656  cubic  inches  =27  cubic  feet  =.00061983  acre-foot  =.76456  cubic  meter. 
I  acre-foot  =325851   U.  S.  gallons  =43560  cubic  feet  =  r6i3i  cubic  yards  =  1233.49  cubic 

meters. 
I  cubic  meter,  stere  or  kiloliter  =  1000000  cubic  centimeters  =  1000  liters  =61023.4  cubic 

inches  =264.17   U.   S.  gallons  =35.3145  cubic  feet  =  1.30794  cubic  yards  =.000810708 

acre-foot. 

HYDRAULICS 

I  U.  S.  gallon  of  water  weighs  8.34  pounds  avoirdupois. 

i  cubic  foot  of  water  weighs  62.4  pounds  avoirdupois. 

I  second-foot  =448.8  U.  S.  gallons  per  minute  =26929.9  U.  S.  gallons  per  hour  =.646317  U.  S. 

gallons  per  day. 
=  60  cubic  feet  per  minute  =3600  cubic  feet  per  houi  =86400  cubic  feet  per 

day  =31536000  cubic  feet  per  year  =.000214  cubic  mile  per  year. 
=  .9917  acre-inch  per  hour  =  1.9835  acre-feet  per  day  =723. 9669  acre-feet  per 

year. 

=  50  miner's  inches  in  Idaho,  Kansas,  Nebraska,  New  Mexico,  North  Dakota, 
and  South  Dakota  =40  miner's  inches  in  Arizona,  California,  Montana, 
and  Oregon  =38. 4  miner's  inches  in  Colorado. 
=  .028317  cubic  meters  per  second  =  1.699  cubic  meters  per  minute  =101.941 

cubic  meters  per  hour  =2446. 58  cubic  meters  per  day. 
I   cubic  meter  per  minute  =.5886   second-foot  =4.403   U.   S.   gallons  per  second  =1.1674 

acre-feet  per  day. 
I  million  gallons  per  day  =  1.55  second-feet  =3.07  acre-feet  per  day  =2. 629  cubic  meters 

per  minute. 

second-foot  falling  8.81  feet  =  i  horse-power, 
second-foot  falling  10  feet  =  1.135  horse-power, 
second-foot  falling  1 1  feet  =  i  horse-power,  80  per  cent  efficiency, 
second-foot  for  i  year  will  cover  i  square  mile  1.131  feet  or  13.572  inches  deep, 
inch  deep  on  I  square  mile  =2323200  cubic  feet  =.0737  second-foot  for  I  year. 


CONVENIENT  EQUIVALENTS.  617 

MISCELLANEOUS 

I  foot  per  second  =.68  mile  per  hour  =  1.097  kilometers  per  hour. 

I  avoirdupois  pound  =7000  grains  —.4536  kilogram. 

I  kilogram  =1000  grams  =.ooi  tonne  =15432  grains  =2.2046  pounds  avoirdupois. 

{15  pounds  per  square  inch. 
i  ton  per  square  foot. 
I  kilogram  per  square  centimeter. 
Acceleration  of  gravity,  &  =32.16  feet  per  second. 
I  mil  =.ooi  inch. 

i  circular  mil  =— (.ooi)2  or  .0000007854  square  inch. 
4 

i  square  inch  =1273240  circular  mils. 

No.  10  Birmingham  gage  wire  has  a  diameter  of  134  mils  and  a  cross-sectional  area  of 
17956  circular  mils. 

i  horse-power  =5694120  foot-gallons  per  day  =550  foot-pounds  per  second  =33,000  foot- 
pounds per  minute  =  108,000  foot-pounds  per  hour  =2545  B.T.U.  per  hour  =76  kilo- 
grammeters  per  second  =  1.27  kilogrammeters  per  minute  =746  watts. 

i  horse-power  boiler  rating,  requires  the  evaporation  of  343  pounds  per  hour  of  water  at 
212°  F.  to  dry  steam  at  the  same  temperature;  or  the  expenditure  of  33,317  B.  T.  U.; 
and  in  practice  is  developed  by  burning  3!  to  4$  pounds  per  hour  of  coal  under  10  to 
12  square  feet  of  heating  surface. 

I  B.T.U.  =778  foot-pounds. 

i  pound  of  bituminous  coal  contains  about  14,100  B.T.U.  or  11,000,000  foot-pounds  of 
energy. 


INDEX 


"A"  frame  dams  described,  384 
Abandoned  irrigated  lands,  185 
Acoustic  current  meter,  156 
Acre-foot,  definition  of,  165 

—  table  of  equivalents,  616 
Acre-inch,  definition  of,  165 
Advantages  of  irrigation,  5 
Agricultural    Department    experiments 

on  duty  of  water,  143-145 
Agua  Fria,  underground  waters,  47 
Air  in  running  water,  293 
Air-lift  pumping,  92 
Alcohol  pumping  engines,  85,  86 
Aldershot,  sewage  irrigation  at,  126 
Alexander,  W.  H.,  book  by,  63 
Alfalfa  as  a  nurse  crop,  105,  106 

—  as  preventive  of  alkali,  13 
Algeria,  area  irrigated  in,  4 
Alinement  of  canals,  212-215 
Alkali,  concrete  lining  protection,  238 

—  in  canals,  prevention  of,  521 

—  or  injurious  salts,  8-15 

—  rise  of,  brief  discussion,  190,  191 

—  resistance  to,  table,  11,12 

—  tests  of  cement  pipe,  199,  200 
Alkaline  salts,  discussion  of,  8-15 

—  soils,  effect  on  metal,  308-314 
Allegheny  River,  flow  and  area,  592 
Allier  River,  France,  flood,  595 

All  Saints  Church,  pressure  on  founda- 
tion, 447 

Alluvial  soils,  definition  of,  7 
Alvord,  J.  W.,  book  on  floods,  63 
Ambursen  type  dam,  mention,  487.   See 

Hollow  Dams. 
American  River,  flood  and  area,  593 

—  flow  of,  42 
Folsom  dam,  385 


American  Society  of  Agricultural  Engi- 
neers, data,  148 
Analysis  of  soils,  table,  9 

—  Shoshone  Dam,  illustrated,  474 
Ancient  irrigation  works,  mention,  2 
Androscoggin  River,  flood  and  area,  592 
Anticlinal  valley  as  reservoir  site,  345 
Application  of  water  to  land,  111-136 
Appropriation,  water,  doctrine  of,  496- 

500 
Appurtenance    to    land,    water    rights, 

500,  501 

Aquatic  plants,  growth  of,  521-524 
Aqueduct,  Ganges  Canal,  India,  301 

—  Nadrai,  India,  313 

—  Strawberry  Valley,  illustrated,  336 
Arabs,  irrigation  by,  in  Sahara,  62 
Arch  Bridge  pressures,  447 

—  dam,  definition  of,  443 

—  dams,  design  of,  469-474 

—  spillway,  East  Park,  485 

Ardeche  River  flood,  France,  355,  595, 

596 
Areas  irrigated  in  countries,  table,  4 

—  reservoirs,  table,  598 

--  river  drainage  basins,  592-596 
Argentina,  area  irrigated,  4 
Arizona  Canal,  data  about,  230 
Arkansas  River,  flow  of,  42 
Arrowhead  Dam,  height  and  length,  599 

—  Reservoir,  evaporation,  71 
Arrowrock  coffer  dam,  illustrated,  402 

—  Dam,  and  gunnite,  452 

—  balanced  valve,  365 

—  data,  600 

—  plans  and  section,  458-460 

—  pressure,  447 

—  specifications,  535-546 

—  Reservoir,  area,  cost,  etc.,  598 


619 


620 


INDEX 


Arroyo  Seco,  flood  and  area,  594 
Artesian  areas,  50,  51 

—  wells,  48-59 

—  books  on,  63,  64 

Ash  Fork  Dam,  Arizona,  487-490 

—  data,  600 

Ashti  Dam,  India,  data,  599 
Asse  River,  France,  flood,  595 
Assiout  Dam,  Egypt,  data,  600 
Assuan  Dam,  data,  600 

—  silt  removal  at,  376,  377 

—  steel  canal  below.  241,  242 
Assyria,  records  of  irrigation  in,  2 
Auckland  Dam,  data,  600    • 
Aupa  River,  Germany,  flood,  596 
Ausable  River,  flood  and  area,  593 
Australia,  area  irrigated  in,  4 

—  Goulburn  Weir,  397 

—  Rainfall  records,  356 

—  regulator  gates  in,  254 
Australian  salt-bush  and  alkali,  13 

—  water  meter,  177 

Austrian   Soc.    E.   and   Arch.,  pressure 

data,  447 
Automatic  recording  gage,  160,  161 

—  shutters  and  gates,  392 

—  spillways,  275-277 

-  Tieton,  280-282 
Avalon  Dam  failure  explained,  422 

—  Reservoir,  area  and  capacity,  598 
Azischos  Dam,  data,  600 

Azusa  hydrant  meter,  173 


B 

Babylonia,  records  of  irrigation  in,  2 
Backfilling  over  drain  tiles,  197 
—  specification  clause,  559 
Bacteria,  sewage  irrigation  and,  128 
Badana  Dam,  data,  600 
Baker,  I.  O.,  pressure  data,  447 
Baker,  M.  N.,  book  on  sewage,  64 
"Baffle  piers"  at  dams,  477,  478 
Balanced  valves,  360,  365 
—  illustrated,  364-369 
Balmorhea  Dam,  data,  599 
Ban  Dam,  France,  data,  600 
Barage  du  Nil,  mention  of,  387 


Bargaglino  Cr.,  Italy,  flood,  596 
Bark,  Don  H.,  address  by,  26 

—  article  by,  15 

—  book  by,  152 

—  bulletin  by,  183 

—  seepage  data,  234 
Barker  Dam,  data,  600 
Barossa  Dam,  data,  6co 

—  pressure,  447 

Barrin  Juick  Dam,  data,  600 
Basic  Creek,  flood  and  area,  594 
Bassano  Dam,  design  mention,  477,  478 
Baum  Co.,  F.  G.,  constant  angle  dam, 

472 

Bazin  formula,  pipe,  326 
Beacon  Brook,  N.  Y.,  flood,  595 
Bear  River,  flood  and  area,  594 

—  flow  of,  44 

—  canal  drop,  285 

—  crib  dam,  illustrated,  401 

Bear  Grass  Creek,  flood  and  area,  594 
Bear  Valley  Dam,  plan  and  section,  473 

pressure  on,  447 

Bear  Valley  Dams,  Big  and  Little,  600, 

601 

Beaumont  rice  pumping  plant,  98 
Beavers,  first  dam  makers,  382 
Beetaloo  Dam,  data,  600 
"Before  and  After"   irrigation  views, 

IOO-IOI 

Belle  Fourche  Dam,  paving,  illustrated, 
418 

—  material  used,  423 

—  gravel  blanket  on,  436 

—  outlet  works  of,  358 

—  section  of,  406 

—  Reservoir  data,  598 

—  tunnel  data,  334 

Bench  marks,  specification,  clause,  553 
Beneficial  uses  of  water,  law  of,  497,  499 
Berlin,  deep  well  near,  51 
Betwa  Dam,  India,  data,  600 

—  weir  flashboards,  illustrated,  393  * 
Bezwara  Weir,  India,  section,  391 
Bhatgur  Dam,  India,  data,  600 

Big  Bear  Valley  Dam,  data,  600 
Bigelow,  F.  H.,  paper  on  evaporation,  71 
Billings,  Mont.,  analysis  soils,  9 


INDEX 


621 


Bjorling's  formulas  for  water  wheels, 

80,  82 

"Black  Alkali,"  definition  of,  8 
Black  Lick  River,  flood  and  area,  594 
Bleone  River,  France,  flood,  595 
Bligh,  W.  G.,  book  by,  495 

—  pressure  data,  447 

Blue  Nile,  irrigation  waters  of,  25 
Boat  gaging  station,  illustrated,  162 
Bober  Dam,  Germany,  data,  600 

—  River,  Silesia,  flood,  595 

Boise  canal  dam  and  gates,  illustrated, 

255 

—  chute  and  stilling  basin,  291 

—  pipe  manufacture,  illustrated,    328, 

329 

—  project,  cost  of  canal  lining  on,  243. 

See  also  Arrowrock  Dam. 

—  River,  flow  of,  43 

—  hydrograph  of,  34 

—  Valley,  analysis  soils,  9 

—  ground  water  charts,  186-189 
steel  flume  in,  307 

Bond,  specification  clause,  548 
Boonton  Dam,  N.  J.,  data,  600 
Border  methods  of  irrigation,    112-117, 

124 

Borings,  dam  foundations,  493,  494 
Borrow  pits,  specification  clause,  558 
Bowman  Dam,  data  and  section,  437, 

599 

Bow  River,  flow  of,  44 
Box  turnout,  U.  S.  R.  S.,' plans,  267 
Boyds  Corner  Dam,  data,  600 
Brasimone  Dam,  data,  600 
Brazil  rainfall  records,  356 
Breaks  in  canals  discussed,  271 
Breast-wheels,  description  of,  81 
Bridge  Pont-y-Prydd,  pressure  on,  447 
Bridgeport  Dam,  data,  600 
Bridges  over  canals,  335-337 

—  steel,  specifications,    579-584 
Briggs,  L.  J.,  book  by,  25 

investigations  of,  20,  21 

Broad  River,  flood  and  area,  593 
Brodie  data  on  masonry  pressure,  447 
Brooklyn  Bridge,  pressure  on,  447 
Brown,  Hanbury,  books  by,  152,  527 


Buck  scraper,  description  of,  229 
Buckley,  R  B.,  book  on  irrigation  by,  71 
Budlong  Creek,  N.  Y.,  flood  and  area, 

595 

Buech  River,  France,  flood  and  area,  595 
Bumping  Lake  Dam  data,  598 

—  section,  433 

Burdick,  C.  B.,  book  on  floods,  63 
Bureau  of  Soils,  analyses  by,  9   • 
Bureau  of  Standards  alkali  tests,    199, 

200 
Burkholder,  J.  L.,  article  by,  201 

—  Chart  of  Rio  Grande,  187,  1 88 
Burns  Creek,  superpassage,   illustrated, 

3i6 

Burrin  Juick  Dam,  pressure,  447 
"Burro"  Dam  described,  382 
Burrowing  animals,  525,  526 
Butterfly  valves,  illustrated,  362,  366, 

367 
By-pass,  Umatilla  Canal,  288 


Cabbage  Tree  Dam,  data,  600 
Cable  station,  stream  gaging,  161 
Cache  La  Poudre,  flow  of,  42 

—  seepage  to,  245 
Cain,  Wm.,  book  by,  495 
Cairo,  Barage  du  Nil  near,  387 
Calaveras  Dam,  data,  599 

—  failure  of,  429,  430 

—  River,  flood  and  area,  594 
Calcium  carbonate  and  alkali,  14 
California,  irrigation  in,  book  on,  63 

—  rainfall  records,  356 

—  State  Board  of  Health,  5 

—  stovepipe  well  drilling,  57 
Galloway  Canal,  Cal.,  silt  in,  25 

—  weir  at,  388-390 
Camp,  specification  clause,  537 
Canada,  area  irrigated  in,  4 
Canada  Creek,  W.,  N.  Y.  flood,  594 
Canal  cross  sections,  illustrated,  204 

—  lining,  236-245 

—  losses  and  prevention,  233,  234 

—  riders,  duties  of,  503 

—  specifications,  557-559 

—  structures,  chapter  on,  247-369 


622 


INDEX 


Canal   superintendent,  duties  of,   502, 

503 

—  zone,  rainfall  records,  357 
Canals,  list  of  U.  S.  R.  S.,  230-232 

—  and  laterals,  chapter  on,  202-246 
Cane  Creek,  flood  and  area,  594 
Canvas  Dam  used  in  irrigation,  112,  113 
Canyon  Creek  Dam,  Utah,  data,  599 
Capillarity  of  soils,  table  of,  18 
Capillary  movement  in  soil,  16,  17,  1 8 
Carbon  dioxide  in  tunnel,  335 
Carbonate  of  sodium,  8,  n 

Carey  Act,  mention  of,  3 
Carlsbad  canals,  lining  and  costs,  242 
Carpenter,  L.  G.,  book  on  duty  of  water, 
152 

—  bulletins  by,  182,  246 

—  experiments,  return  seepage   by, 

245 
Carson  River,  East,  flow  of,  43 

—  regulator,  251-257 
Carver's  data  on  hydraulic  rams,  92 
Casey,  Col.  T.  L.,  masonry  pressure,  447 
Casselman  River,  flood  and  area,  593 
Cast-iron  specifications,  563 

—  gates,  lateral  illustrated,  269 
Castlewood  Dam,  section,  438 
Cataract  Dam,  data,  600 

Catawba  River,  flood  and  area,  592,  593 
Catskill  Creek,  flood  and  area,  594 
Cattaraugus  Creek,  flood  and  area,  593 
Cavour  Canal,  Italy,  views,  298 
Cedar  River,  flood  and  area,  594 

—  flow  of,  44 

Cement  drains,  use  of,  198-200 

—  gun  work,  Arrowrock  Dam,  452 

—  lining  canals,  coefficient.  235 
Cement,  specification  clause,  536,  537, 

559,  565,  566 
Centrifugal  pumps,  86-90 
Certified  check,  specification  clause,  547 
Chagres  River,  flood  and  area,  593 
Chamberlain,  T.  C.  report  on  wells,  63 
Chandler,  A.  E.,  book  by,  501 
Changes,  specification  clause,  550,  551 
Chapter  House,  Elgin,  pressure  on,  447 
Charges  for  water,  basis,  514,  515 
—  U.  S.  R.  S.  table,  146 


Chartrain  Dam,  data,  600 
Chattahoochee  River,  flood  and  area, 

592,  593 

Chaustiere  Dam,  data,  600 
Cheat  River,  flood  and  area,  593 
Check  and  farm  turnout,  illustrated,  264 
Check  system  of  irrigation,  Salt  River, 

illustrated,  122 
Checks,  drops  and  chutes,  282-290 

—  used  in  irrigation,  illustrated,  116 
Chemical  properties,  metal,  578 
Chemung  River,  flood  and  area,  592 
Cherry  Creek,  Colo.,  water  supply,  59 
Cherryvale  Creek,  Kansas,  flood,  595 
Chezy  formula,  163 

China,  mention  of  irrigation  in,  2,  4 

—  rainfall  at  Hongkong,  356 
Chinamen,  market  gardening  of,  58 
Church,  Irving  P.,  book  on  fluids,  182 
Chute  or  inclined  drop,  212 
Chutes,  checks  and  drops,  282-290 
Chuviscar  Dam,  Mexico,  data,  600 
"Cienegas,"  term  for  swamps,  194 
Cippoletti  weir,  book  on,  182 

—  definition  of,  166,  167 

—  formula  for,  167 

Clarion  River,  flood  and  area,  593 
Clarke,  Sir  Andrew,  masonry  data,  447 
Classification,  masonry  dams,  443 
Clay  in  hydraulic  fill  dams,  428 
Clay,  used  in  earth  dams,  423 
Cleaning  canals  of  silt,  520,  521 
Cleaning  up,  specification  clause,  553 
Clear  Lake  Reservoir,  data,  598 
Clearing  of  irrigable  lands,  104 
Clentangy  River,  flood  and  area,  593 
Climatic  conditions,  specifications,  552 
Climatology  of  U.  S.,  book  on,  63 
Closed  drains,  definition  of,  191 
Coast  Range  and  rainfall,  28 
Coefficient  of  roughness,  602,  603 
Coefficients  of  friction,  table,  448 
Coffer  dam,  Arrowrock  Dam,  402 

—  specification  clause,  544 
Coghlan,  silt  data,  371 

Cohoes  Iron  Weir,  section,  486,  489 
Cold  Spring  Earn,  building,  illustrated, 
427 


INDEX 


623 


Cold  Springs  Dam,  flood  at,  355 

—  Reservoir  data,  598 
Colorado  River,  bulletin  on,  63 

—  flow  of,  42 

headgates,  251,  253,  256 

—  value  of  silt  of,  25 
Columbia  River  flow  of,  43 

—  maximum  flow  of,  592 
Compressed  air  used  in  pumping,  92 
Compression,  on  masonry,  447 
Concentrated  crest  spillway,  illustrated, 

274 

Conconully    Dam,    flumes   used,   illus- 
trated, 431 

—  outlet  works,  359,  360 

—  section  of,  435 

—  Reservoir,  water  records,  40 

—  tunnel  data,  334 
Concrete,  canal  lining,  237-245 

—  gravel,  pressure  on,  447 

—  pipe  specifications,  574-576 

—  specifications,  540-543*  559~56i 

—  turnout,  lateral,  illustrated,  270 
Cone,  V.  M.,  bulletin  by,  183 

—  flume  invented  by,  179 
"Constant  angle"  dams,  472,  473 

—  Dam,  book  on,  495 
Construction,  earth  dams,  424-426 
Continuous  stave  pipe,  324 
Contract  specifications,  text  of,  547-554 
Contracted  orifice,  definition  of,  169 
Contraction  joints,  concrete  lining,  237 

—  in  dams,  453 

Contractor,  specification  clause,  548 
Contractor's  bond,  specification  clause, 

548 

Coolgardie  Dam,  data,  600 
Cooperation  with  water  users,  504 
Coosawattee  River,  flood  and  area,  593 
Corbett  Dam,  cross  section,  248,  249 
-  Tunnel,  data,  334 
Core  wall,  concrete,  Kachess  Dam,  414 

—  concrete,  Minidoka  Dam,  436 

—  earth,  Bumping  Lake,  433 

—  gravel  in  dam,  423 

—  puddle,  Conconully  Dam,  435 

—  steel,  Otay  Dam,  438 

Core  walls,  earth  dams,  discussed,  422 


Corrugation  system  of  irrigation,  119, 

120 
Cost,  clearing  lands,  104-106 

—  drainage  ditches,  article  on,  201 

—  drains,  U.  S.  R.  S.,  200,  201 

—  earth  dams,  table,  599 

—  estimates  of,  projects,  531-533 

—  leveling  land,  1 10 

—  lined  canals,  U.  S.  R.  S.,  242,  243 

—  masonry  dams,  table,  600,  601 

—  puddling,  canal  lining,  243 

—  pumped  irrigation  water,  511 

—  Reservoirs  of  U.  S.  R.  S.,  598 

—  silting  porous  canals,  244,  245 

—  tunnels,  built  by  U.  S.  R.  S.,  334 

—  water,  Reclamation  Service  projects, 

146 

—  well  drilling,  57 

Cosumnes  River,  flood  and  area,  593 
Cottonwood  Creek,  flood  and  area,  594 
Coulon  River,  France,  flood  and  area, 

595 

Court  decision,  Salt  River,  149 
Covell  Creek  Dam,  Australia,  data,  601 
Cowgill's  diagram  of  flood  irrigation,  117 
Creager,  W.  P.,  book  by,  495 
Creager's  compressive  tests,  446 
Crib  dams,  illustrated,  401,  402 
Crib  work,  underground,  59,  60 
Cronholm,  F.  N.,  article  by,  201 
Crops  and  duty  of  water,  139-142 
Crossings,  drainage,  293-299 
— ,  highway,  335-337 
Cross  River  Dam,  data,  600 
Cross-section  and  subgrade,  210-212 
Croton  Dam,  cross-section,  464 

,  N.  Y.,  data,  601 

,  Old,  section,  479 

Croton  Falls  Dam,  data,  600 
Croton  watershed,  paper  on,  380 
Crowley  Creek  Dam,  data,  600 
Cuba,  rainfall  records,  3^7 
Cubic  foot  per  second,  definition,  165 
Cultivation  and  duty  of  water,  140,  141 
Cultivation  under  irrigation,  515,  516 
Culverts,  irrigation  canals,  314-323 
Current  meter  measurements,  171.  172 
Current  meters,  description  of,  155-163 


624 


INDEX 


Current  wheel  on  Salmon  River,  89 
"Cusec"  definition  of,  165 
Cuyamaca  Dam,  data,  599 
Cylinder  drop,  Franklin  Canal,  289 

D 

D'Arcy  pipe  formula,  326 
Dalles,  flow  Columbia  at,  592 
Dabrowka  Creek,  Austria,  flood,  596 
Damages,  specification  clause,  552 
Dams,  canvas  and  steel,  for  irrigation, 

113 

—  chapters  on,  381-495 

—  list  of  books  on,  495 

—  submerged,  61 

—  tables,  height,  cost,  etc.,  599-601 

—  underground  water,  61 

Darton,  N.  H.,  report  on  deep  borings, 

63 

— ,  underground  water,  47 
Davis,  A.  P.,  books  by,  98,  201,  380 
Dean  and  Follansbee,  bulletin  by,  63 
Deer  Flat  Embankment,  cross  section, 

416 
Deer  Flat   Embankment,  gravel  face, 

illustrated,  418 

Deerfield  River  flood  and  area,  593 
Deerflat  Reservoir,  area,  cost,  etc.;  598 

—  leakage,  347~349 
Defective  work,  specifications,  553 
Dehree  Weir,  India,  illustrated,  391 
Del  Rio,  Texas,  pumping  plant,  95-97 
Delaware  River,  flow  and  area,  592 
Delays,  specification  clauses,  549,  550 
Derwent  Dam,  Eng.,  data,  600 
Deschutes  River,  book  on,  63 

flow  of,  43 

outlet,  Tumalo,  347 

Desert  Land  Act,  mention  of,  3,  497 
Design,  Masonry  Dams,  455,  475 
Dethridge  meter  for   measuring   water, 

175-176 

Devil's  Creek,  flood  and  area,  594 
Devil's  River,  flow  of,  44 
DeVries,  analysis  of  soils  by,  9,  10 
Dew  Point,  definition  of,  27 
Diamond  drilling  dam  foundations,  494 
Direct  explosion  pumps,  95-97 


Discharge    measurements    of    streams, 

154-157 

Discharge  records  of  streams,  42-44 
Ditch  riders,  duties  of,  503 
Ditcher,  "V"  illustration  of,  107 
Ditching,  irrigable  lands,  no 
Ditching  machine,  view  of,  228 
Diversion  dams  or  weirs,  382-404 

— ,  overfall,  475-490 
Dixville  Dam,  data,  599 
Domodossola  Dam,  Italy,  data,  599 
Drag  line  excavator,  view  of,  192 
Drainage  area,  effect  of,  40 

—  of  rivers,  592-596 
Drainage,  books  on,  list,  201 
— ,  chapter  on,  184-201 

—  crossings,  293-299 

— ,  irrigation  and  health,  5,  6 

—  systems,  design  of,  193-198 
Drains,  classification  of,  191-193 
Drake,  E.  F.,  report  by,  183 
Drilling  dam  foundations,  493-495 
Drilling  wells,  methods,  53-57 
Drop  and  turnout,  canal,  268 

— ,  canal,  pump  at,  90 
Drops,  checks  and  chutes,  282-290 
"Dry  lakes,"  formation  of,  345 
DuBois,  A.  Jay,  book  translated  by,  183 
Durance  River,  France,  flood,  595 

—  Valley,  value  silt  in,  25 

Duryea,  Edwin,  paper  on  evaporation, 

7i 
Duty  of  sewage  water  for  irrigation,  130 

—  water,  books  on,  list,  15,  152 
,  chapter  on, 137-152 

Dyer,  C.  W.  D.,  paper  on  weirs,  182 


Eads  Bridge,  pressure  on  piers,  447 
Earth,  evaporation  from,  69,  70 
Earthen  dams,  discussion  of,  405 
Earthquakes,  rock-fill  dams  and,  441 
Earthwork,  specification  clauses,  556- 

559 

East  Carson  River,  flow  of,  43 
East  Park  Dam,  data,  600 

—  spillway,  482,  485,  486 
—  Diversion  Dam,  view,  482 


INDEX 


625 


East  Park  Reservoir,  area,   cost,  etc., 

598 

Economy  of  water,  504-511 
Eder  River,  Germany,  flood,  595 
Edinburg,  sewage  irrigation  at,  126 
Egin  Bench  subirrigation,  133 
Egypt,  abandoned  irrigation  lands  in, 

185 

—  area  irrigated  in,  4 

—  book  on  irrigation  in,  71 

—  records  of  irrigation  in,  2 

—  reference  to  irrigation  works,  v 

—  steel  lined  canals  in,  241,  242 
Einsidedel  Dam,  data,  600 

Electric  power,  specification  clause.  537 
Elephant  Butte  Dam,  data,  600 
— •,  cross  section,  454 

—  construction,  455,  462 

—  design  against  uplift,  453 

—  pressure,  447 

—  Reservoir,  table  data,  598 

—  silt  in  discussed,  377-380 
Elkhorn  Cr.,  flood  and  area,  594 
Elliott,  C.  G.,  Bulletin  by,  201 
Elevating  grader,  view  of,  228 
Embankments,  rules  for,  405.     See  also 

Deer  Flat. 

Engineer,  specification  clause,  543 
Engines  for  pumping,  84-86 
Ensign,  balanced  valve,  360,  365 
Eolian  soils,  definition  of,  7 

—  type  of  land,  219 
Erosion  and  canal  design,  214 

—  prevention  of,  in  canals,  519,  520 

—  protection  against,  290-295 
Escondido  Dam,  data,  599 
Esopus  Cr.,  flood  and  area,  594 
Estacado  Dam,  paper  on  grouting,  495 

—  pressure  on,  447 
Estanzuela  River,  Mexico,  flood,  595 
Estimates    and    reports,    specifications, 

536 

—  of  cost  of  project,  531-533 
Etcheverry,  B.  A.  books  by,  15,  26,  98, 

136,  246 

— ,  lined  canal  experiments  by,  242 
— ,  silt  data  by,  373 
Eucalyptus  globulus,  effect  of,  6 


Evaporating  pan,  illustration  of,  67 

Evaporation  and  rainfall,  41 

• — ,  books  on,  list  of,  71 

— ,  chapter  on,  65-72 

—  table,  cities  of  U.  S.,  69 

— ,  table  on,  by  months,  72 

Evaporometer,  observations,  68 

Excavating  machinery,  views  of,  192 

Excavation,  specification  clauses,  538- 

540 
Expansion  joints,  concrete  lining,  237 

-  in  dams,  453,  457-461 
Experience,  specification  clause,  551 
Explosion,  pumps,  direct,  95-97 
Extra  work,  specification  clause,  550 
Eyach  River,  Germany,  flood,  596 


Failure,  masonry  dams  discussed,  444, 

447,  449 

Famine  in  India,  185 
Fanning,  J.  T.,  book  by,  182 

— ,  pressure  data,  447 
—  discharge  formula,  596 
Farm  laterals,  construction  of,  no 
Farm  turnout  and  check,  illustration, 

264 
Fay  Lake  outlet  works,  illustration,  360, 

361 
Feather  River,  flood  and  area,  592 

— ,  flow  of,  42 

"  Federal  vs.  Private  irrigation,"  6 
Fernow,  B.  E.,  evaporation  data  by,  70 
Fertility  and  soil  surveys,  101-103 
Fertilizing  effect  of  sediments,  25 
Fertilizing  effects  of  sewage,  1 28,  1 29 
Filtration,   intermittent    method,    126, 

127 
Financial       obligations,       specification 

clause,  551 

Fippin  and  Lyon,  book  by,  26 
— ,  analysis  of  soils  by,  9 
Fish  Cr.  N.  Y.,  flood  and  area,  594 
Fish  screens,  Umatilla  project,  483 
Fishkill  Cr.,  flood  and  area,  59^ 
Fitzgerald,   Desmond,  evaporation  ex- 
periments, 66 
Flashboard,  automatic,  dams,  392,  393 


626 


INDEX 


Flashboard  weirs,  388-390 

— ,  Laguna  gates,  illustrated,  253 

—  use  of,  257 

Flathead  project,  sink  holes,  224-226 
Fleming,  \V.  B.  book  on  pumps,  98 
Flinn,  A.  D.,  paper  on  weirs,  182 

—  book  by,  380 

Flint  River,  flood  and  area,  593 
Float,  for  leveling,  illustrated,  no 
Floats,  stream  measurement,  155 
Flood  discharges,  table  of,  592-596 

—  flows  of  rivers,  examples,  355-358 

—  prevention,  reference  to,  380 
Floods  and  spillways,  354-358 
— ,  books  on,  63,  64 

Flooding  method  of  irrigation,  in.  112 
Florida,  subirrigation  in,  135,  136 
Flow  of  water,  books  on,  182,  183 

— ,  tables,  604-610 

Fluctuations  of  ground  water,  186-189 
Flume,  Bear  River  Canal,  295 

—  concrete,  standard  plans,  296 

—  steel,    Uncompahgre    Valley,    illus- 

trated, 322 

—  tables,  hydraulic  data,  613 
Flumes,  chapter  on,  299-308 

—  metal,  specifications,  576-579 
Flynn,  P.  J.,  book  on  irrigation  canals, 

182 

Follensbee  and  Dean,  bulletin  by,  63 
Follett,  W.  W.,  article  by,  380 

—  book  on  silt  by,  26  ' 

—  Rio  Grande  silt,  379-380 

—  silt  data  of,  371 

Folsom  canal  gates,  illustrated,  262 

—  and  weir,  illustrated,  383,  385 

—  Dam,  data,  600 

Food  for  plants,  chapter  on,  22-26 
Foote  measuring  weir,  173-175 
Forbes,  R.  H.,  bulletin  by,  26 
Foreign  countries,  area  irrigated,  4 
Forms,  concrete,  specifications,  561 

—  pipe,  Boise  project,  illustrated,  329 
Formula,  arch  dams,  469 

—  canal  design,  202 

—  erosion  and  canal  design,  214 

—  flood  discharge,  596,  597 

—  flow  in  pipe,  326,  330 


Formula,  flow  in  turnout,  268,  269-271 

—  Kutter's,  602,  603 

—  lateral  capacity,  221 

—  loss  of  head  siphon,  318 

—  orifices,  1 70 

—  seepage  losses,  235 

—  siphon  spillway,  275 

—  stream  measurement,  163-170 

—  thickness  of  dam,  456 

—  velocity  head,  614 

—  weirs,  167,  168 

Fort  Shaw  canal  spillway,  illustrated, 

277 
Fortier,  Sam'l,  books  by,  6,  26,  136-152 

—  bulletins  by,  71,  246 

—  on  duty  of  water,  148 

—  percolation  of  water  by,  48 
Foundation,  earth  dams,  405-409 
Foundations,  masonry  dams,  490-493 

—  pressures  on,  447 

Fox  Cr.  Crossing,  L.  Yellowstone,  illus- 
trated, 320 

France,  area  irrigated  in,  4 
— ,  examples  of  silt  in,  25 
— ,  flood  flows  in,  355 
Francis  formula  for  weirs,  167 
Franklin  Canal,  cylinder  drop,  289 
Free  board  of  canal  banks,  210 
French  open  weirs,  illustrated,  394,  396 
Fresno  scraper,  view  of,  109 
Friction,  coefficients,  table  of,  448 
Friez  recording  stream  gage,  160 
Frozen  streams,  measurements  of,  162, 

163 

Furens  Dam,  France,  data,  600 
-  River,  France,  flood,  596 
Furrow  Irrigation,  bulletin  on,  15 

—  in  Idaho,  illustrated,  125 

—  methods,  117-119 

—  system  irrigation,   Cal.,   illustrated 


G 

Gaging  streams,  153-157 

Galvanized  sheets,  advantages  of,  309 

Ganges  Canal  aqueduct,  301 

—  super  passage,  311 

—  weirs,  sections,  391 


INDEX 


627 


Ganguillet  and  Kutter  formula,  164 
Garden  City  windmill  and  reservoir,  88 
Garland  Canal,  dimensions,  232 

—  turnout,  268 

Gas  engines  for  pumping,  84.  85 
Gas  tar,  waterproofing  dam  with,  453 
Gasoline  pumping  engines,  85,  86 
Gate,  cast  iron,  lateral  illustrated,  269 
Gate  House,  Conconully  Dam,  360 
Gates,  canal  wood  and  metal,  250-254 
— ,  reservoir,  illustrated,  361-369 
Gatun  Dam,  design  mentioned,  407-477 

—  data  on,  411,  412 

—  volume  of,  599 
Gem  Lake  Dam,  data,  600 
Geologic  structure  and  rainfall,  41 
Geological  Survey  current  meters,  156 

—  stream  flow  records,  39 
Geology,  reservoir  sites,  344-346 
German  patent  roller  dams,  394 
Gila  River  report  of,  380 

-  stream  flow  records,  42 
Gillepe  Dam,  Belgium,  data,  600 
Glacial  soils,  definition  of,  7 
Glatzer  Neisse  River,   Germany,   flood, 

595 

Godivery  Weir,  India,  section,  391 
Goldbach  River,  Germany,  flood,  596 
Goodwin  Dam,  Cal.,  data,  600 
Goodyear  Cr.,  flood  and  area,  595 
Gorzente  Dam,  data,  600 
Goss,  Arthur,  soil  book  by,  26 
Goulburn  Canal  gates,  Australia,  254 
—  Weir,  Australia,  illustrated,  397 
Grade  of  lands  for  irrigation,  100 
Grader,  elevating,  view  of,  228 
Grand  River,  flow  of,  42 

—  Dam,  illustrated,  396-400 
Grand  Valley  canals  lining,  243,  244 

—  lands  subsidence,  225 

—  tunnels,  data,  334 
Grande  Ronde  River,  flow  of,  44 
Granite  ashlar,  pressure  on,  447 
Granite  Reef  Dam,  plan  and  section,  476 

—  in  flood,  481 

Granite  Springs  Dam,  data,  600 
Grant-Mitchell  meter,  177 
Gravel  core,  view  Sherburne  Dam,  434 


Gravel  protection,  Deer  Flat  Reservoir, 

4i5-4i7 

Grease  wood,  presence  of,  102,  104 
Great  Forks,  analysis  soils  at,  9 
Great  Salt  Lake,  origin  irrigation,  2 
Greaves,     Chas.,     evaporation    experi- 
ments, 66 

Green,  J.  S.,  report  by,  182 
Green  River,  flow  of,  44 

—  hydrography,  35 

—  water  wheels  on,  80 
Gregory,  W.  B.,  book  on  pumps,  98 

—  pump  data,  87 
Grinnell  well  in  Paris,  50 
Ground  water  fluctuation,  186-189 

—  required  depth  to,  195 

—  supply  for  pumping,  74 
Grouting  dam  foundations,  492,  493 

—  foundations,  sp  cifications,  542,  543 
Grover,  N.   C.  &  J.  C.  Hoyt,  book  by 

Messrs.,  63,  182 

Gunnison  tunnel,  data,  334,  335 
"Gunnite"  on  face  /Yrrowrock  Dam,  452 
Gurley  recording  stream  gage,  160 
Gypsum  and  alkali,  14,  15 

—  formation,  reservoirs  in,  345,  349,  350 

—  leakage  of  canals  in,  227 

H 

Habra  Dam,  Algiers,  data,  600 
Haehl,  H.  L.,  evaporation  report,  71 
Hale's  Bar  Dam,  data,  600 
Hall,  W.  H.,  book  on  irrigation  in  Cali- 
fornia, 63 

Hamlin,  Homer,  book  on  Salinas  Valley, 
64 

—  underflow  tests,  63 

Hamlin's  chart  of  California  rainfall,  33 
Hanna,  F.  W.,  article  by,  246 

—  hand  book  by,  183 

—  recording  meter,  1 73 

Happy  canyon  steel  flume,  illustrated, 

322 

Harding,  S.  T.  O.  and  M.,  book  by,  527 
Harrison,  C.  L.,  paper  by,  495 
Hart,  R.  A.,  bulletin  by,  201 
Haskell  current  meter,  155,  156 
Hatfield  Dam,  data,  600 


628 


INDEX 


Hauser  Dam,  New,  Mon.,  data,  601 
Hawaii,  area  irrigated  in,  4 
Hawaiian  Islands,  article  on,  98 

—  pumping  plant,  86 

Hay,  Prof.  Robt.,  well  reports,  63 
Hazen,  Allen,  formula,  46,  47 
Head,  loss  of,  formula,  318 
Head  gates,  canal  248-262 
Headworks,  canal,  247-262 
Health  and  irrigation  discussed,  5,  6 

—  sewage  irrigation,  129,  130 
Height  of  Dams,  table  of,  599-601 
Hellreigel's  data  on  plant  water,  23 
Hemet  Dam,  valve  plug,  illustrated,  362 
Hemlock  Dam,  data,  600 

Henne  Dam,  Germany,  data,  600 
Henny,  D.  C.,  article  by,  6 

—  flume  invented  by,  1 78 
Henry,  A.  J.,  book  by,  63 

—  precipitation  charts  by,  36,  37 
Henshaw,  Lewis,  bulletin  by,  63 
Herndon,  Cal.,  stream  flow  at,  33 
Highway  crossings,  335-337 
Hilgard,  E.  W.,  book  by,  15 

—  bulletin  by,  26 

—  soil  experiments  by,  14,  15,  21 
Hill,  Louis  C.,  meter  invented  by,  176 
Hill,  Prof.  Robt.  T.,  book  by,  63 

—  meter  for  measuring  water,  176 
Himalaya  Mts.,  rainfall  in,  357 
Hindia  Barrage,  data,  600 
History  of  irrigation,  2-4 
Hiwassee  River,  flood  and  area,  593 
Hollister,  G.  B.,  bulletin  by,  183 
Hollow  concrete  dams,  478-487 
Holyoke  Dam,  section  of,  475 
Hondo  Reservoir,  leakage,  350 
Hoosic  River,  flood  and  area,  593 
Horse-power  equivalents,  616,  617 
Horseshoe  Bend  Dam,  data,  599 

—  section,  hydraulic  tables,  612 
Horton,  R.  E.,  weir  tables,  182 
Hot  air  pumping  engines,  85,  86 
Hotzenplotz  River,  Germany,  flood,  595 
Howden  Dam,  England,  data,  600 
Hoyt,  J.  C.,  article  by,  on  rainfall,  63 

—  and  Grover,  N.  C.,  book  by,  63, 
182 


Hoyt,  J.  C.,  bulletin  by,  183 
Huacal  Dam,  Mexico,  data,  600 
Hudson  River,  flow  and  area,  592,    93 
Hughes,  D.  E.,  report  by,  380 

—  silt  data,  371,  373 
"Human  side  of  irrigation,"  6 
Humboidt  River,  flow  of,  43 
Hume-Bennett  Dam,  data,  600 
Humphrey,  direct-explosion  pump,  95- 

97 

Humphrey,  H.  A.,  article  by,  98 
Humus,  lack  of,  8 
Huntley,  duty  of  water  at,  147 

—  pumping  plant,  90 
Hydrant,  Azusa,  meter,  173 
Hydraulic  data  tables,  611-617 

—  books  on,  64,  182,  183 

—  equivalents,  table,  616,  617 

—  fill  dams,  426-436 

—  formulae,  163-170 

—  jump,  Granite-reef  Dam,  481 

—  radius  in  canals,  205 

—  radius  tables,  604-613 

—  ram,  data,  91,  92 

—  rams,  Yakima  Valley,  88,  92 
Hydro-electric  pumping,  92,  95 
Hydrographers,  duties  of,  503,  504 
Hydrographic  manual,  183 
Hydrographs  of  rivers,  33-35 
Hydrology,  books  on,  63,  495 
Hydrometric  surveys,  reports  on,  183 
Hydrostatic  uplift  on  dams,  451-453 
Hygroscopic  water,  in  soils,  16,  17 


I 

Ice,  measuring  streams  through,  163 

—  pressure  in  dam  design,  paper  on,  495 

—  pressures  on  dams,  450,  451 

—  snow  and,  evaporation  of,  68 
Imperial  Valley  silt  conditions,  222 
India,  area  irrigated  in,  4 

—  book  on  irrigation  in,  6,  71 

—  famine  and  malaria  in,  185 

—  notch  drop  in,  284 

—  rainfall  records  of,  356 

—  reference  to  irrigation  works  of,  v 

—  unit  of  flow,  "cusec,"  165 


INDEX 


629 


India,  wells,  irrigation  from,  58.      See 

Ganges  Canal. 
Indian  Government's  investigations,  5 

—  type  weirs,  illustrated,  390,  391 

—  River  Dam,  N.  Y.,  data,  600 
Ingot  iron,  effect  of  alkali  on,  309 
Injurious  salts  or  alkali,  8-15 
Inspection  gallery  specifications,  54-56 
— ,  specification  clause,  551 
Integration  method  of  stream  measure- 
ment, 7.58 

"Intermittent  filtration"  methods,  126, 

127 

Internal  combustion  engines,  84,  85 
Interstate  Canal  flume,  303,  308,  310 

—  gates,  illustrated,  251 

—  headworks,  259 

—  lateral  gates,  269 

—  lining,  view,  239 

—  sections,  204 

—  siphons,  illustrated,  317,  318 
Investigation  of  a  project,  528-533 
lola,  Kans.,  stream  flow  at,  34 
Irawaddy  River,  India,  flood,  596 
Iron  pipes,  subirrigation  by,  136 
Iron  weir,  Cohoes,  section,  486,  489 
Irrigable  lands,  chapter  on,  99-110 
Irrigation,    books    on.     See    end    each 

chapter. 

—  definition  of,  i 

" — Institutions,"  book,  501 

—  methods  of,  111-136 

—  rotation  methods,  512-514 

—  rules,  Utah,  150-152 
Italians,  market  gardening  by,  58 
Italy,  area  irrigated  in,  4 

J 

Jackson,  L.  D'A.,  book  by,  64 
Jackson  Lake  Dam,  view  of,  260 

—  Reservoir,  area,  cost,  etc.,  598 
Jaffa,  M.  E.,  soil  experiments  of,  13 
Jamaica  rainfall  records,  356 
James,  George  Wharton,  book  by,  6 
James  River  Valley  Wells,  51 
Japan,  area  irrigated  in,  4 

—  rainfall  records,  356 
Java,  area  irrigated  in,  4 


Jerome  Reservoir,  leakage,  351 
John  Day  River,  flow  of,  44 
Johnson  grass  and  sheep,  525 
Johnston,  C.  T.,  book  by,  501 
Jorgenson,  L.  R.,  book  by,  495 

—  on  arch  dams,  469 
Jorgenson's  arch  design,  484 

Jump,  hydraulic,  Granite-reef  Dam,  481 
Jumper,  clearing  lands  of,  105 

K 

Kachess  Dam,  cross  section  and  data, 
414,  420 

—  Reservoir,  data,  598 

Keechelus  Dam  outlet,  illustrated,  366 

—  Reservoir  data,  598 
Kennebec  River,  flood  and  area,  592 
Keno  Canal  spillway,  illustiated,  274 
Kensico  Dam,  N.  Y.,  data,  600 

—  pressure,  447 

Keokuk  Dam,  Iowa,  data,  600 
Kern  River,  flow  of,  42 

—  diversion    weir,    illustrated,    388, 

389 

Khojok.Pass,  tunnel  for  water,  59 
Khrishna  River,  India,  flood,  596 
Kinder  River  Dam,  data,  599 
King,  F.  H.,  book  by,  15,  201 
King's  data  on  plant  water,  23 

—  River,  flood  and  area,  593 
— ,  flow  of,  42 

Kingman,  Ariz.,  dam  at,  403,  404 
Kiskiminetas  River,  flood  and  area,  593 
Klamath  project,  Lost  River  Dam,  252 

—  project  spillway,  illustrated,  274 

—  tunnel  data,  334 

Kneale  and  Tannatt,  bulletin,  201 
Kuichling,  Emil,  paper  by,  63 

—  formula  discharge,  596 

—  Prof.,  flood  records,  358 
Kutter's  formula,  164 

—  for  pipe,  326 

—  tables,  602-610 


La  Boquilla  Dam,  Mexico,  data,  601 
La  Grange  Dam,  Cal.,  data,  601 
—  section,  480 


630 


INDEX 


La  Jalpa  Dam,  Mexico,  data,  601 
La  Mesa  Dam,  data,  599 
Labrador,  evaporation  in,  65 
Lagastrello  Dam,  Italy,  data,  599 
Laguna  Dam  headgates,  illustrated,  251, 
253,  256 

plan  and  section,  386,  387 

Lahontan  Dam  outlet,  illustrated,  363 
plan  of,  408 

—  Reservoir,  data  table,  598 

Lake  Bonneville,  settlement  of  canal  at, 

227 

Lake  Cheesman  Dam,  data,  601 
Lake  Conchos,  evaporation  on,  71 
Lake  Fife  Dam,  India,  data,  601 
Lake  McMillan,  leakage,  349,  350 
Lakes  as  reservoir  sites,  342,  343 
Lands,  irrigable,  chapter  on,  99-110 
Landslides  on  canals,  526,  527 

—  values,  effect  on  irrigation,  3 
Laramie  River,  flow  of,  44 

—  Dam,  data,  599 

—  Reservoir,  flood  and  area,  594 
Larue,  E.  C.,  bulletin  by,  63 
Las  Vegas  Dam,  data,  599 
Lateral  canal  systems,  217-224 
Laterals,  canals  and,  chapter  on,  202-246 
— ,  farm,  construction  of,  no 
Lauchensee  Dam,  data,  601 

Lava,  reservoir  site  in,  345,  351 

Law  of  water,  chapter  on,  496-501 

Lawes  and  Gilbert's  data  on  water,  23 

Lawson,  silt  data,  371 

Leaching  of  soils,  12-13 

Leakage,  canal,  discussed,  224-227 

—  reservoir,  discussed,  346-354 
Leasburg  Canal  gates,  illustrated,  250 

— ,  sand  box,  illustrated,  339 

—  diversion  weir,  section,  478 
Leffel  turbine,  water-wheel,  83 
Leipsic,  deep  well  near,  51 

Length  of  season  and  duty  of  water,  138 
Leveling  irrigable  lands,  107-110 

—  of  land,  necessity  for,  103 
Lewis,  John  H.,  book  by,  501 

Lick  Observatory  Records  of  rainfall, 

356 
Lined  canal,  Okanogan,  illustrated,  321 


Lined  canal  section,  211,  213 
Lining  canals,  236-241 

—  steel,  canal,  Egypt,  241,  242 
Lippincott,  J.  B.,  book  by,  380 
Lister  Dam,  Germany,  data,  601 
Lithgow  Dam,  pressure,  447 

Little  Bear  Valley.     See  Bear  Valley, 

601 
Little  Tennessee  River,  flood  and  area, 

593 
Local   conditions,   specification   clause, 

55i 

Lock-bar  pipe  described,  326 
Log  hoist,  specification  clause,  546 
Loire  River,  flood  of,  355 
Los  Angeles,  sewage  irrigation,  130 
Losses,  canal  and  prevention,  233,  234 

—  early  irrigation,  3 

—  seepage/ 234-236 

Lost  River  and  Tule  Lake,  352 

—  diversion  works,  illustrated,  252 
Loughridge,  R.  H.,  book  by,  15,  26 

—  investigations  of,  n,  12,  20 
Louisiana,  rice  irrigation  in,  86,  97,  98 
Low-head  pumping  plants,  86 
Lower  Otay  Dam.     See  Otay. 
Lower  Yellowstone  Canal  drop,  287 

—  sluiceway,  278 

—  culverts,  illustrated,  315,  316 

—  Dam,  section,  387 

—  pipe  inlet,  294 

—  sand  gate,  340 

—  siphon,  illustrated,  320 
Lyon,  analysis  of  soils  by,  8 
Lyon  and  Fippin,  book  by,  15,  26 

—  experiments  on  soil,  18 

M 

McAdie,  A.  G.,  book  on  rainfall,  64 
McAlester  Dam,  data,  599 
McCall's  Ferry  Dam,  section,  480 
McCausland,  bulletin  by,  63 
McCloud  River,  flood  and  area,  593 
McDowell,  Ariz.,  stream  flow  at,  35 
MacMillan  Dam,  data,  599 

—  Lake,  data,  598 

—  Reservoir,  leakage,  349.  350 
Mahan,  F.  A.,  book  on  water  wheels,  98 


INDEX 


631 


Maintenance,  operation  and,  chapter, 

502-527 

—  work,  when  to  do,  518,  519 
Malaria,  effects  of  irrigation,  5,  6 

—  in  India,  185 
Malheur  River,  flow  of,  43 
Malleable  castings,  specifications,  564 
Manholes,  drain  lines,  197,  198 
Manning,  Robt.,  book  by,  64 
Marklissa  Dam,  Germany,  data,  601 
Masonry  Dams,  chapter  on,  442-495 

—  table  of  data,  600,  601 
Material   and   workmanship    specifica- 
tions, 548-549 

Mauer  Dam,  Germany,  data,  601 
Mead,  D.  W.,  book  by,  63,  183 

— ,  rainfall  tables,  32 
— ,  Elwood,  book  by,  501 

—  bulletins  by,  152,  246 

Means,  Thos.  H.,  water  investigations, 

62 

Measurement  of  irrigation  water,  153- 
183 

—  water  to  the  user,  164,  165 
Measuring  devices,  165-182 

—  vi2w  of,  detail  of,  263 

—  water,  books  on,  182-183 
Medina  Dam,  Texas,  data,  601 
Meer  Allum  Dam,  plans  of,  472 
Merced  Dam,  Cal.,  data,  599 

—  River,  flood  and  area,  593 
Mercedes  Dam,  Mexico,  data,  601 
Mesquite,  clearing  land  of,  104 
Metal  flumes,  specifications,  576-579 

—  work,  specification  clauses,  545,  546 
Meters  for  measuring  water,  155-163 

—  water  works  not  suitable,  172 
Meyer,  A.  F.,  book  by,  495 

—  voids  in  rock,  491 

Miami  Valley  floods,  work  of,  354,  355 
Mill  Brook,  N.  Y.,  flood  and  area,  595 

—  Creek,  Pa.,  flood  and  area,  594 
Mineral  food  for  plants,  23,  24 
"Miner's  inch,"  and  duty  of  water,  149 

—  definition  of,  165 

—  value  of,  616 
Minidoka  Canal  gate,  250 

—  Dam,  section  of,  436 


Minidoka  project,  lateral  system,  218, 
219 

—  silting  canals,  244,  245 

—  pumping  plant,  93-95 

—  Reservoir,  area,  cost,  etc.,  598 
Minitare   Darn  outlet,  illustrated,  362, 

366 

—  Reservoir,  table  data,  598 
Missouri  River,  flow  of,  43 
"Modoc  Lava  Beds,"  leakage,  352 
Moehne  Dam,  Germany,  data,  601 
Mohawk  River,  flood  and  area,  592 
Moisture  in  soil,  16-21 
Monocacy  River  flood  and  area,  593 
Monongahela  River,  flow  and  area,  592 
Montrose  and  Delta  Canal  headgates, 

260 

Morena  Dam,  data,  599 
Morin's  coefficients  of  friction,  448 
Moritz,  E.  A.,  articles  by,  183,  246 
Morris  Dam,  Conn.,  data,  599 
Morrison  data  on  pressure,  447 
Moselle  River,  France,  flood,  595 

—  Valley,  value  silt  in,  25 
Mosquitoes  and  irrigation,  5,  6 
Mountain  Dell  Dam,  Utah,  data,  601 
Mulching  and  alkali,  14 

—  evaporation,  66 

Mullins.  Lieut. -Gen.  J.,  book  by,  182 
Murphy,  D.  W.,  article  by,  201 

—  E.  C.,  bulletins  by,  98,  183 
Murgab  Valley,  abandoned  lands,  185 

—  headgates  in,  261 


N 

"N"  value,  Kutters  formula,  164,  602, 

603 

Nadrai  Aqueduct,  India,  313 
Narora  weir,  India,  illustrated,  391 
Narrows  Dam,  uplift  data,  453 
Navier's  formula,  arches  469 
Necaxa  Dam,  Mexico,  data,  599 

—  failure,  428,  429 
Neches  Canal  pumping  plant,  98 
Needle  valves,  illustrated,  362,  368 
Neosho  River,  flood  and  area.  592 
—  flow  of,  34,  43 


632 


INDEX 


Nettleton,  E.  S.,  book  by,  64 

New  Croton  Dam.     See  Croton  Dam. 

New  Dam,  Mexico,  data,  601 

New  Hauser  Dam,  Mon.,  data,  601 

New  River,  flood  and  area,  592 

Newell,  F.  H.,  artesian  well  report,  64 

—  article  by,  6 

books  by,  98,  152,  527 

—  report  by,  183 

Newell  and  Murphy,  book  by,  98 
Nicaragua,  report  en    hydrography   of, 
380 

—  of  rainfall,  357 

—  silt  experiments,  374-376 
Night  irrigation,  511,  512 
Nile,  barage  on,  at  Cairo,  387 

—  Valley,  silt  irrigation  in,  25 
Nitrates  and  plant  food,  23,  24 
Nitrogen  and  plant  food,  24 
Norwich  Water  Co.,  Dam,  section,  477 
North     Platte.     See     also     Interstate 

Canal 

—  Whalen  Dam,  257,  259 

—  River,  flow  of,  44 

Notch  drop,  India,  illustrated,  284 

Interstate  Canal,  286 

Nurse  crop  of  alfalfa  and  rye,  105,  106 


O 

O'Shaughnessy,  M.  M.,  article  by,  98 
Ocmulgee  River  flood  and  area,  592 
Oconee  River,  flood  and  area,  594 
Oder  Dam,  Germany,  data,  601 

—  River,  Germany,  flood,  595 
Ohio  River,  flow  of,  592 

Oil  lining,  canals,  coefficient,  235 
Okanogan     Canal,     lining,    illustrated, 
321 

—  project,  chute,  294 

—  irrigation  methods,  513 

—  tunnel  data,  334 

Okhla  weir,  India,  illustrated,  391 
Old  Croton  Dam.     See  Croton  Dam. 
Olive  Bridge  Dam,  N.  Y.,  data,  601 

—  pressure  on  foundation,  447 
Ontario  Colony,  Cal.,  water  supply,  59 
Open  and  closed  weirs,  386-388 


Open  drains,  definition  of,  191 
Operation   and    maintenance,   chapter 
on,  502-527 

—  charges,  U.  S.  R.  S.,  146 
Optimum  water  supply,  18-20 
Orange  grove  irrigation,  illustrated,  122 
Oregon,  water  supply  of,  book  on,  63 
Organization,  specifications  of,  535,  536 
Orifices,  measuring  168-172 

—  formulae,  170 

—  table,  1 80,  181 

Orland  project,  lined  canal,  O.  &  M. 

costs,    242.     See    also    East    Park 

Dam. 

Orme,  Dr.  H.  O.,  investigations  of,  5 
—  S.  H.,  sewage  irrigation  book,  64 
Otay  Dam,  core  wall,  438,  440 

—  failure  of,  441 

—  lower  length,  height  and  volume, 

599 

—  views  of,  439,  440,  471 
Outlet  works,  reservoir,  358-369 
Overfall  dams,  illustrated,  475,  490 
Overhaul,  specification  clause,  558 
Overshot  water-wheels,  81,  82 
Overturning,  failure  of  dams  by,  449 
Owl  Creek  Dam,  gravel  blanket,  436 

—  material  used,  423 

—  outlet  works,  359 

—  paving,  illustrated,  418 

—  section  of,  406.     See  also  Belle 
Fourche. 

Owyhee  River,  flow  of,  43 


Pacific  Slope,  rainfall  on,  32-34 
Pacoima  Creek,  dam  on,  403 
Paris,  deep  well  in,  50 
Pas  Du  Riot  Dam,  France,  data,  601 
Pasadena,  Cal.,  sewage  irrigation,  130 
Passaic  River,  flood  and  area,  593 
Patents,  specification  clause,  553,  554 
Pathfinder  Dam,  Wyo.,  data,  601 

—  view  of,  470 

—  Reservoir,  area,  cost,  etc.,  598 
Pecos  Irrigation  Co.,  canals,  leakage, 
227 


INDEX 


633 


Pecos  River,  flow  of,  44 
— ,  Lake  McMillan,  349 

—  Valley  Dams,  data,  599 
Pelton  water  wheels,  84 
Peguonnock  Rivei,  flood,  594 
Percolation  of  water  in  dams,  417-423 

—  in  soils,  48 

—  rate  of,  46,  47 

—  views  of,  123 
Periar  Dam,  India,  data,  601 

—  section,  463 

Permeability  of  soils,  table,  47 
Persia,  records  of  irrigation  in,  2 
Peru,  area  irrigated  in,  4 
Philippines,  area  irrigated  in,  4 

—  rainfall  records,  356 

Piche  evaporometer  observations,  68 

Pilarcitos  Dam,  data,  599 

Pile  weirs  described,  384,  387 

Piling,  specification  clause,  544,  545 

Pinal  Creek,  flood  and  area,  594 

Pinon,  clearing  lands  of,  105 

Pipe,  concrete,  specifications,  574-576 

—  formulae  discussed,  326,  330 

—  irrigation,  sub-irrigation,  134,  135 

—  manufacture,  illustrated,  328,  329 

—  steel,  specifications,  572-574 

—  turnouts,  U.  S.  R.  S.,  plans,  266 

—  vitrified,  specifications,  590,  591 

—  wood  stave,  specifications,  567-571 
Pipes,  concrete,  metal  and  wood,  323- 

330 

—  flow  of  water  in,  paper  on,  183 
Piscataquis  River,  flood,  594 
Pishkun  tunnels,  data,  334 
Plant  food,  chapter  on,  22-26 

—  growth  and  water,  22,  23 
Platte  River,  cribwork  on,  59,  60 
Plowing  as  remedy  for  alkali,  13 

Po  Valley  Canal  structures,  Italy,  298 
Pocolet  River,  flood  and  area,  594 
Pomona,  Cal.,  irrigation  at,  98 
Pompton  River,  flood  and  area,  594 
Poncelot  water  wheels,  81 
Potassium  and  plant  food,  23,  24 
Potholes  in  canals,  224,  225 
Potomac  River,  flow  and  area,  592 
Powder  River,  flow  of,  43 


Powell,  J.  W.,  report  on  wells,  64 
Precipitation  charts  of  U.  S.,  36 

—  in  U.  S.,  maps  of,  29-31 
Prehistoric  irrigation  works,  2 
Preparation  of  land  for  irrigation,  104- 

no 

—  and  duty,  140 
Preparing  land,  bulletin  on,  136 
Pressures  on  masonry,  table,  447 

—  dams,  444-447 
Price  current  meter,  155-157 
Price  River,  flow  of,  44 
Priming  canals,  Grand  Valley,  243,  244 
"Principles  of  irrigation  practice,"  book, 

6 

"Private  vs.  Federal  irrigation,"  6 
Profits  of  irrigation  discussed,  4,  5 
Progress  of  work,  specification  clause, 

536 

Project  manager,  duties  of,  502 
Proposal,  specification  clauses,  547 
Prosser  siphon  and  bridge,  illustrated, 

327 

Protection  of  earth  dams,  413-417 
Protection  of  work,  specification  clause, 

553 

Provo  River,  flow  of,  44 
Puddling,  cost  in  lining  canals,  243 

—  specification  clause,  559 
Pumping,  books  on,  98 

—  for  irrigation,  73-98 
Pumps,  centrifugal,  86-90 
Purchase  specifications,  555-556 
Putah  Creek,  flood  and  area,  593,  594 


Quantities,  specification  clause,  552 
Queis  River,  Germany,  flood,  595,  596 

R 

Rafter,  Geo.  W.,  book  on  sewage,  64 
Rainfall  and  duty  of  water,  138,  139 

—  books  on,  63,  64 

—  character  of,  41 

—  discussion  of,  27-37 

—  excessive,  records,  356,  357 

—  government  projects,  145 

—  of  Cal.,  report  on,  64 


634 


INDEX 


Rainfall  records,  tables,  356,  357 

—  runoff  and,  40,  41 

—  U.  S.  maps  of,  29-31 

Ram.     See  Hydraulic  ram,  91,  92 
Ramapo  River,  flood  and  area,  594 
Rands,  H.  A.,  paper  by,  495 
Raritan  River,  flood  and  area,  593 
Rating  curve  for  stream  measurement, 

162 

Rawhide  crossing,  illustrated,  317 
"Reclaiming  the  arid  West,"  book,  6 
Reclamation  Act,  passage  of,  3 
" —  Record,"  article  on  water,  152 
Reclamation  Service,  canal  linings,  238- 
244 

—  canals,  table  of,  230-232 

—  drainage  problem,  185 
drains,  table  of,  200,  201 

—  duty  of  water,  144,  145 

—  O.  &  M.  charges,  table,  146 

—  pipe  formulae,  330 

—  pumping  plant,  90 

—  reservoirs,  598 

—  spillway  standards,  272,  273 

—  turnouts,  plans,  266-270 
Reconnaissance  of  project,  528 
Recording  water  meters,  172-179 
Redwood  for  pipe  discussed,  324 
Regulator  gates,  canal,  250-256 
Reinforced  concrete  dams,  478-487 
Reinforcement  bars,  specifications,  559, 

562 

Remedies  for  alkali,  12-15 
Remscheid  Dam,  table  of  data,  60 1 
Reports  and  estimates,   specifications, 

536 
Reservoirs,  built  by  U.  S.  R.  S.,  table, 

598 

—  storage,  chapter  on,  342-369 
Residual  soils,  definition  of,  7 
Return  flow  measurements  of,  245,  246 
Returns  of  irrigation,  4,  5 

Rhine  River,  Switzerland,  flood,  595 
Rice  irrigation,  97,  98 

—  pumping  for,  86 

—  production  in  U.  S.  by  States,  97 
Right  of  way,  specification  clause,  553 
Rio  Das  Lages  Dam,  data,  601 


Rio  Grande,  bulletin  on,  63 

flow  of,  42-44 

silt,  book  on,  26 

,  data,  25,  371,  372 

—  deposits,  377-379 
— ,  Panama,  flood,  595 

—  Valley,  duty  of  water  in,  147 

—  seepage,  185 

—  water  fluctuation,  187 

—  wells  in,  58 

Rio  Mora,  flood  and  area,  593,  594 
Riparian  doctrine  of  water  right,  496 
River  discharge,  books  on,  63 
Riverside,    Cal.,    irrigation   illustrated, 

115,  122 

Rivers,  flood  discharge  table,  592-596 
Road  crossings,  335-337 
Roads  and  fences,  specification  clause, 

553 

—  on  canal  banks,  210 

—  specification  clause,  537 
Rockfill,  specification  clause,  545 

—  dams,  436-441 

—  table  of.  599 

Rock  sections  of  canals,  207,  208 
Roller  dams,  illustrated,  394-400 
Rolling  earth  dams,  425,  426 

—  view  of,  427 

Rondout  Creek,  flood  and  area,  594 
Rookery   Building.    Chicago,    pressure, 

447 

Roosevelt  Dam,  plan  and  section,  467, 
468 

—  table  of,  data,  601 

—  pressure  on,  447 

—  Reservoir,  area,  capacity,  etc.,  598 
Rotation  system  of  irrigation,  182,  512- 

5i4 

Run-off,  laws  of,  40-45 
Russell,  T.,  evaporation  experiments,  68 
Russia,  area  irrigated  in,  4 
Russian  thistle,  pest  0^.524,  525 
Rye  as  a  nurse  crop,  106 
Ryves,  Col.,  discharge  formula,  597 


St.  Louis  Bridge,  pressure  on,  447 
St.  Louis,  deep  well  in,  51 


INDEX 


635 


St.  Mary  Lake  Dam,  mixture,  for,  420 
St.  Paul's,  London,  pressure  on,  447 
St.  Peter's,  Rome,  pressure  on,  447 
Sacaton  grass  and  alkali,  10 
Sacramento  River,  flow  and  area,  592 

—  flow  studied,  42,  354 
Safety  conditions  of  dams,  381,  382 
Sagebrush  indication  of  fertility,  102, 104 
Sahara  Desert,  waters  of,  62 

Salinas  Valley,  Cal.,  report  on,  64 
Salmon  River,  current  wheel  on,  89 

—  Dam,  data,  601 

—  design,  472,473 
Salt-bush  and  alkali,  13 

Salt  Lake,  origin  of  irrigation  at,  2 
Salt  River,  flow  and  area,  592 

—  hydrograph  of,  35,  42 

—  Project,  irrigation,  513 

—  Valley,  court  decision,  149 

—  duty  water  in,  147 

—  irrigation,  illustrated,  122,  124 

—  value  of  silt  of,  25 
Salton  Sea,  evaporation  on,  72 
Salts,  injurious,  and  alkali,  8-15 
San  Andres  Dam,  data,  599 
San  Carlos  Project  report,  380 
San  Diego  flume,  Cal.,  302 

San  Fernando  submerged  dam,  403 
San  Gabriel  River,  flood  and  area,  594 

—  flow  of,  42 

San  Joaquin  River,  flow  of,  33,  42 

—  River,  flood  and  area,  593 

—  Valley,  windmills  in,  75 
San  Jose  Dam,  Mexico,  data,  601 
San  Luis  Rey,  Cal.  River,  flood,  593 

—  Valley,  abandoned  lands,  185 

—  sub-irrigation,  133,  134 

San  Marcial,  Rio  Grande,  silt  at,  372 
San  Mateo  Dam,  Cal.,  data,  601 

—  plans  and  section,  466 
San  Pablo  Dam,  data,  599 
San  River,  Austria,  flood,  595 
Sand,  specifications,  560 

Sand  boxes,  illustrated,  338-340 
Sand  traps,  canal,  337-341 

—  and  manholes,  197 
Sandstone,  pressure  on,  447 
Sandy  land  in  soil  surveys,  103 


Sandy  regions,  clearing  of,  105-106 
Sanitary  works,  books  on,  64 
Sanitation,  specification  clause,  553 
Santa  Ana  Canal  lining,  237,  240 
—  sand  box,  338 

—  flume,  Cal.,  302,  304 

—  River,  flow  of,  42 

Santa  Catarina  River,  flood,  593 
Santa  Ysabel  Creek,  flood,  594 
Saturation  of  earth  dams,  409-411,  419- 

423 

—  hydraulic  fill-dams,  428 

—  soil  discussed,  19 
Savannah  River,  flow  and  area,  592 
Saw,  submarine,  weeds,  523 
Sawmill,  specification  clause,  537 
Schantz,  H.  L.,  book  by,  25 
Scheidenhelm,  F.  W.,  paper  by,  495 
Scheidenhelm's    coefficient    of   friction, 

448 

Schlichter  &  Wolf,  book  by,  98 
Schlichter's  experiments  on  soils,  48 
Schoharie  Creek,  flood  and  area,  593 
Scioto  River,  flood  and  area,  593 
Schuyler,  J.  D.,  book  by.  380 

—  gates  designed  by,  360-362 

—  pressure  data,  447 
Scobey,  F.  C.;  bulletin  by,  183 
Scoop  wheels,  90,  94,  95 
Scraper,  Fresno,  view  of,  109 

—  slip,  illustration  of,  106 
Screw  pump,  87 

"Seal,"  water,  of  tunnel,  331 

Season,  length,  and  duty  of  water,  138 

"Second  foot,"  definition  of,  165 

—  table  of  equivalents,  616 
Sections  of  canals,  illustrated,  204 
Sediment  rolled  along  bottom,  373-376 
Sedimentation  of  Reservoirs,  370-380 

—  tank  for  sewage,  131 
Sediments,  fertilizing  effect  of,  25 
Seepage  in  dams,  417-423 

—  formulae,  235 

—  losses,  canal,  202,  234-236 

—  reservoir,  discussed,  346-354 

—  Rio  Grande  Valley,  147 

—  signs  of,  185-191 

Seine,  open  weirs  on,  387,  394 


636 


INDEX 


Seligman  Dam,  Ariz.,  data,  601 
Seros  Project  Dams,  data,  599 
Settlement    of    lands,    Grand   Valley, 

225 
Sevier  River,  flow  of,  44 

—  Dam,  data,  599 
Sewage  disposal,  123-127 

—  farms,  laying  out  of,  130-133 

—  fertilizing,  effect  of,  128,  129 

—  irrigation,  125,  127,  128 

—  books  on,  64 

—  health  and,  129,  130 
"Sewage  purification  in  America,"  63 
Sheep  used  in  clearing  canals,  525 
Shenandoah  River,  flood  and  area,  592, 

593 
Sherburne  Lake  Dam  material,  423 

—  section,  434 

Shifting  channels  and  stream  measure- 
ments, 159 
Shoshone  Dam,  Wyo.,  data,  601 

—  diagram,  474 

—  pressure,  447 

—  Desert  before  and  after,  100,  101 

—  Project,  Corbett  Dam,  248,  249 

—  Reservoir  data,  598 

—  tunnel,  data,  334 

Shutters,    automatic,   illustrated,    392, 

393 

Siam,  area  irrigated  in,  4 
Sickness.     See  Health  and  Malaria. 
Side  slopes  of  canals,  209 
Sierra  Nevada  Mts.  and  rainfall,  33 
Signature,  specification  clause,  547 
Silt  allowance  in  canal  design,  203 

—  bearing  water,  effect  of,  25 

—  books  on,  380 

—  conditions,  Imperial  Valley,  222 

—  deposits  in  canals,  520,  521 

—  removal  from  reservoirs,  376-380 

—  table  of  weight  of,  371 
Silting  leaky  canals,  244,  245 

—  of  reservoirs,  370-380 
Sink  holes,  leakage  from,  350 

—  in  canals,  224-227 

Siphon  spillways,  illustrated,  275-277 
Siphons,  large  canal,  317-320 
Six-mile  Creek,  flood  and  area,  594 


Six-tenths  of  depth  method  of  measur- 
ing stream  flow,  158 
Slichter,  C.  S.,  underground  waters,  64 
Slichter's  percolation  experiments,  419 
Sliding  failure  of  dams,  447-449 
Slides  of  canal  banks,  526,  527 
Slip  scraper,  illustration  of,  106 
Slope  of  lands  for  irrigation,  100 
Slopes  of  earth  dams,  409-417 
Sluiceway,    Lower    Yellowstone,    illus- 
trated, 340 

—  standard  design,  278 
Snake  River,  flow  of,  43 
Canyon,  leakage  to,  351 

—  Dam,  section  of,  436 

—  power  plant  on,  93-95 
Snow  and  ice,  evaporation  on,  68 
Snowfall,  effect  on  stream  flow,  37,  38 
Soane  Canal  sluice  gate,  illustrated,  395 

—  weir  flashboards,  illustrated,  392 
Sodium  carbonate,  effects  of,  1 1 

—  sulphate  and  alkali,  14 
Sodom  Dam,  N.  Y.,  data,  601 
Soil  conditions  and  rainfall,  41 

—  moisture,  chapter  on,  16-21 

—  survey  of  lands,  101-103 
Soils  and  duty  of  water,  139 

—  books  on,  15 

—  chapter  on,  7-15 
Somerset  Dam,  data,  599 

Sorgues  River,  waters  for  irrigation,  25 
South  America,  area  irrigated,  4 
South  Dakota,  largest  well  in,  51 
South  Platte  River,  flow  of,  42 

—  seepage  to,  245 
Spanish  irrigation  systems,  2 
Spaulding  Dam  design,  mention,  473 
Specifications,  chapter  on,  534-591 
Sperenburg  deep  well,  51 
Spiers  Falls,  N.  Y.,  Dam,  data,  601 
Spillway,  East  Park  Dam,  485 

—  provisions,  354-358 
Spillways,  canal,  illustrated,  271-282 
Spiral  lap  seam  pipe,  326 

Sprague  River  Dam,  view  of,  258 
Spring  Canyon  flume,  303,  308,  310 
Spring  Valley  Water  Co.  well  experi 
ments,  59 


INDEX 


637 


Springs  in  foundation  of  dams,  408,  409 
Sprinkling  earth  dams,  425,  426 
Spokane  River,  flow  of,  44 
Spou,  Ernest,  book  on  wells,  64 
Stanislaus  River,  flood  and  area,  593 
Stanley,  F.  W.,  book  on  Florida,  irriga- 
tion, 136 

Starch  Factory  Cr.,  Conn.,  flood,  595 
Stave  pipe  specifications,  566-571 
Steam-power  pumping  engines,  86 
Steam  R.R.,  specification  clause,  537 
Steel  bars,  specifications,  562,  563 

—  bridges,  specifications,  579-584 

—  castings,  specifications,  564 

—  dam  used  in  irrigation,  113 

—  dams,  illustrated,  487-490 

—  flumes,  303-308 

—  lined  canal,  Egypt,  241,  242 

—  mild,  effect  of  alkali  on,  309 

—  pipe,  discussed,  325,  326 

—  specifications,  572-574 

—  structural,  specifications,  561,  562 
Stevens  automatic  stream  gage,  160 
Stilling  basin  and  drop,  291 

Stony  Cr.,  Cal.,  flood  and  area,  593 
Stony  River  Dam,  paper  on,  495 
Storage  dams,  illustrated,  404-436 

—  reservoirs,  chapter  on,  342-369 
-  U.  S.  R.  S.,  table,  598 

—  water  and  evaporation,  70,  71 
Stove  pipe  method  of  well  drilling,  57 
Strange,  W.  I.,  book  on  India,  380 
Strawberry  Dam,  section  of,  410 

—  Reservoir,  data,  598 

—  tunnel,  data,  334 

—  Valley  flume,  illustrated,  310 

—  lined  canal,  illustrated,  336 
Stream  flow,  discussion  of,  37-40 

—  records  in  U.  S.  tables,  42-44 

—  measurement  methods,  153-157 
Structures,  canal,  chapter  on,  247 
Subgrade  of  canals,  210-212 
Sub-irrigation  discussed,  133-136 
Submarine  saw  for  weeds,  523 
Submerged  dams,  illustrated,  402-404 

—  weir,  measuring  water,  166 
Subsidence,  Grand  Valley  lands,  225 
Sub-surface  water  sources,  45-48 


Sugar  beets  and  alkali,  10 
Sugar  Loaf  Dam,  data,  599 
Sulphur  Creek  wasteway,  293 
Sunland  River,  flood  and  area,  595 
Sunlight  in  arid  regions,  2 
Sunnyside  Canal,  dimensions,  232 
Sun  River  tunnels,  data,  334 
Superpassage,  Ganges  Canal,  illustrated, 

3n 

Suppressed  orifice,  definition,  169 
Survey  of  reservoir  sites,  353,  354 

—  stakes,  specification  clause,  553 
Surveys  of  a  project,  528-533 
Suspension  of  contract,   specifications, 

549 

Susquehanna  River,  flow  and  area,  592 
Swamp  reclamation  and  drainage,  185 
Swanzy  Dam,  Wales,  data,  601 
Sweetwater  Dam,  Cal.,  data,  601 
-  spillway,  354,  355 

—  Reservoir,  seepage  into,  246 
—  flood  and  area,  594 

Sweetwater  valve  plug,  illustrated,  362 
Swingle,  Z.  T.,  bulletin  by,  26 
Synclinal  Valley  as  reservoir  site,  345 


Tait,  C.  E.,  bulletins  by,  98,  136 
Talbot,  A.  N.,  article  by,  63 
Talla  Dam,  Scotland,  data,  599 
Tannatt  and  Kneale,  bulletin  by,  201 
Tansa  Dam,  India,  data,  601 

—  River,  India,  flood  and  area,  596 
Teele,  R.  F.,  book  on  land,  136 

—  report  by,  152 
Telephone,  specification  clause,  537 

—  system  specifications,  586-590 
Tennessee  River,  flow  and  area,  592 

—  Little,  flow  and  area,  593 
Tension  in  masonry  discussed,  465 
Ternay  Dam,  Fr.,  data,  601 
Terraced  hillside  irrigation,  illustrated, 

120,  121 

Texas,  rice  irrigation  in,  97,  98 
Theresa  concrete  weir,  section,  486 
Thompson,  S.  E.,  book  by,  495 
Three-mile  Falls  Dam,  plans  and  sec- 
tion, 483 


•638 


INDEX 


Throttle  Dam,  data,  599 
Tieton  Canal  flume  plans,  297 

—  lined  canal,  211,  213 

—  section,  illustrated,  241,  281 

—  steel  flume,  306 

—  tunnels,  data,  334 
Tile  drains,  sizes  of,  191-193 

—  used  in  drainage  work,  196,  197 

—  sub-irrigation,  134,  135 
Timber,  specification  clause,  544 

—  dams,  382-384 

Titicus  Dam,  N.  Y.,  data,  601 
Titles,  water,  496-501 
Toccoa  River,  flood  and  area,  594 
Toncan  metal,  alkali  and,  309 
Topography  and  rainfall,  41 

—  of  irrigable  lands,  99-101 
Trapezoidal  channels,  table  data,  6n 
Trench  excavator  for  drainage,  192 
Trenching  machinery,  bulletin  on,  201 
Triunfo  Creek  Dam,  Cal.,  data,  601 
Truckee  Canal  drop,  illustrated,  283 

—  lining,  view,  240 

—  waste way,  illustrated,  279 

—  River,  flow  of,  43 

Tsar  Canal,  Turkestan,  261 
Tucson,  Ariz.,  sewage  irrigation  at,  128 
Tugaloo  River,  flood  and  area,  593 
Tule  Lake,  leakage  from,  352 
Tumalo  Reservoir,  leakage,  346,  347 
Tumble  weeds  in  canals,  194 
Tunneling  for  water,  59-61 
Tunnels,  discussion  of,  330-335 

—  specification  clause,  538 

—  specifications,  584-586 

—  table  length  and  cost,  334 
Tuolumne  River,  flow  of,  42 

flood  and  area,  593 

Turbine  water  wheels,  82,  83 
Turkestan,  abandoned  lands  in,  185 

—  gates  and  headgates  in,  261 
Turlock  Canal,  cross-section,  207 
Turnouts,  lateral  canal,  263-271 
Turtle  Creek,  flood  and  area,  594 
Twin  Falls  canals  and  leakage,  227 

—  reservoir  leakage,  351 
Tygart  River,  flood  and  area,  593 
Typhoid  fever  and  sewage  irrigation,  1 29 


U 
Ubaya  River,  France,  flood  and  area, 

595 
Umatilla  by-pass  drop,  288 

—  Canal  lining,  view,  239,  243 

—  section,  208 

—  Project,  duty  of  water  on,  147 

—  River,  flow  of,  43 
Uncompahgre  tunnels,  data,  334 

—  Valley  drops,  290 

—  duty  of  water  in,  147 

—  flume,  illustrated,  322 
Underflow  tests,  bulletin  on,  63 
Underground  irrigation,  135,  136 

—  waters,  45-48 

—  books  on,  63,  98 

Undershot  water  wheels,  illustrated,  78- 

81,  89 

Unit  prices,  specification  clause,  552 
United  States,  area  irrigated  in,  4 
Uplift,  hydrostatic  on  dams,  451-453 
Upper  Deer  Flat  Embankment  section, 

416 

Urft  Dam,  Germany,  data,  601 
Urnasch  River,  Switzerland,  flood,  596 
Use  of  water,  doctrine  of,  496,  499 
Use  of  Water  in  Irrigation,"  book,  6 
Utah  experiments  on  duty  of  water,  141- 

143 

—  rules  for  irrigation,  150-152 


V 

"V"  ditcher,  illustration  of,  107 
Valve  plugs,  cast  iron,  dams,  362 
Valves,  butterfly  and  needle.  362-369 
Van  Buren's  stability  of  dams,  451 
Vapor  engines  for  pumping,  84,  85 
Vegetation  and  rainfall,  41.  42 

—  in  canals,  clearing.  521-524 
Velocity  head  tables,  614 

—  in  canals,  discussion  of,  215-217 

—  of  approach  to  weirs,  168 

—  tables,  flow  of  water,  602-610 
Ventilation  of  tunnels,  333 
Venturi  flume,  178,  179 

—  water  meter,  177,  178 

—  formula,   1 78 


INDEX 


639 


Verdun  River,  France,  flood,  595 
Victor  turbine  water  wheel,  83 
Villar  Dam,  Spain,  data,  601 
Vistula  River,  Galicia,  flood,  595 
Vitrified  pipe,  specifications,  590,  591 
Vogesen  Mts.,  rainfall  in,  32 
Voids  in  stone,  491,  492 
Volume  of  Dams,  table  of,  599-601 
Vyrnwy  Dam,  Wales,  data,  601 
—  pressure  on  foundation,  447 

W 

Waco,  Tex.,  artesian  area,  51 
Wachu setts  Dam,  data,  60 1 

—  Reservoir,  permeability,  47 
Waldeck  Dam,  Ger.,  data,  601 
Walnut  Canyon  Reservoir  leakage,  350, 

35i 

Walnut  Grove  Dam,  failure  of,  441 
Wanague  River,  flood  and  area,  594 
War  Department  report,  San  Carlos,  380 
"Wash  borings,"  dam  foundations,  494 
Washington   Monument,    pressure   on, 

447 

Waste  water,  discussed,  511,512 
Waste  ways,  discussion  of,  277,  278 
Water  and  plant  growth,  22,  23 

—  application  of,  to  land,  111-136 

—  character  of,  61-63 

—  concrete  specification  clause,  560 

—  consumed  by  crops,  table,  23 

—  economy  discussed,  504-5 1 1 .       See 

Duty  of  Water. 

—  Law,  books  on,  501 

—  logged  lands,  184,  185 

—  San  Louis  Valley,  133,  134 

—  measurement,  chapter  on,  153-183 

—  proofing  dams,  by  gunnite,  453 

—  rights,  claapter  on,  496-501 

—  supply  and  plant  life,  18-20 

—  chapter  on,  27-64 

—  investigation  of,  528-529 

—  table,  effect  of  rise  of,  10,  n 

—  rise  of,  184,  185 

—  users,  cooperation  with,  504 

—  waste  discussed,  511,  512 

—  wheels,  pumping,  books  on,  98 
pumping  with,  78-84 


Water  works  meters  not  suitable,  172 
Wave  action  on  gravel  slope,  417 
Weather  Bureau,  evaporation  table,  72 
Weber  River,  flow  of,  44 
Weeds,  clearing  canals  of,  521-524 
Weep  holes,  concrete  canal  lining,  237 
Wegmann,  Edward,  book  by,  495 
Weight,  various  substances,  table,  615 
Weights  and  measures  equivalents,  616, 

617 

Weir  formulae,  167,  168 
Weirs  and  coefficients,  books  on,  182, 

183 

—  measuring  water  by,  166-168 

—  or  diversion  dams,  382-404 

—  various  kinds  described,  384-391 
Weisbach,  P.  J.,  book  by,  183 

—  pipe  formula  discussed,  326 
Weiser  River,  flow  of,  43 
Wells,  artesian,  48-59 

—  books  on,  63,  64 

—  deep,  examples  of,  50,  51 

—  in  dams,  drainage,  454  ' 

—  in  drainage  ditches,  194 

—  irrigation  from  in  India,  58 

Werre  River,  Germany,  flood  and  area, 

595 

West  Gallatin  River,  flow  of,  43 
Whalen  Dam,  views  of,   257-259 
Wheel  scraper,  view  of,  425 
Wheels^  water,  for  pumping,  78-84 
Whippany  River,  flood  and  area,  594 
White  Nile,  irrigation  water  of,  25 
Widtsoe,  John  A.,  book  of,  6,  25,  26,  152 

—  bulletin  on  evaporation,  71 

—  O.  &  M.  conclusions,  511 

—  plant  water,  data  on,  23 
Wigwam  Dam,  Conn.,  data,  601 
Willamette  River,  flow  of,  43 
Willcocks,  Sir  William's  visit,  V 
Williams  Dam,  Ariz.",  data,  601 
Willow  Cr.,  Ore.,  flood  and  area,  594 
Wilson,  H.  M.,  books  of,  6,  26,  152 

—  bulletin  by.  98 

—  first  edition  by,  V 

Wilting  coefficient,  definition  of,  20 
Wind  and  evaporation,  68 

—  erosion  of  canal  banks.  524,  525 


640 


INDEX 


Windmills,  books  on,  98 

—  capacity  table,  77,  79 

—  for  irrigation,  75-78 

Wind  pressures,  tables  of,  76,  77 
Winter  operation  of  canals,  516-518 
Wire    reinforcement,   pipe,   illustrated, 
328 

—  wound  wooden  pipe,  324 
Wofelsbrund  Dam,  Ger.,  data,  601 
Wolff,  A.  R.,  book  on  windmill,  77 
Wollny,  data  by,  on  plant  water,  23 
Wood  stave  pipe  siphon,  illustrated,  312 

—  specifications,  566-571 
Wooden  drains,  use  of,  198 
Workmen,  specification  clause,  552 
Workmanship,  specification  clause,  548, 

549 
Wupper  River,  Germany,  flood,  595 


Yadkin  Narrows  Dam,  data,  601 
—  River,  narrows  dam  at,  453 


Yakima  County,  water  appropriation, 
498 

—  River,  flow  of,  44 

—  tunnels,  data,  334 

—  Valley,  analysis  soils  of,  9 

—  furrow,  irrigation,  118 

—  hydraulic  rams,  92 

—  siphon,  illustrated,  327 
Yarnell,  D.  L.,  bulletin  by,  201 
Yellowstone  Dam,  lower,  387 

—  River,  flow  of,  43 
Youghiogheny  River,   flood  and  area, 

593 

Yuba  River,  flood  and  area,  593,  594 
Yuma,   Ariz.,   furrow   irrigation,   illus- 
trated, 119 

—  Canal    headgates,    illustrated,    251, 

253,  256] 

—  siphon  spillway,  276 


Zola  Dam,  Spain,  data,  601 
Zuni  Dam  failure,  352 


$*?. 


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